One number is one-third more than one-half, and the other is four-thirds. What is the sum of these two numbers_

A number is (1 / 2) × (1 + 1 / 3) = 2 / 3
So the sum of these two numbers is 2 / 3 + 4 / 3 = 6 / 3 = 2

One half of a number is four fifths. To find this number, the formula is

Four fifths divided by one half will do
The formula is 4 / 5 (1 / 2) = 8 / 5

Does the formula 1 + 8 = 9 + 9 hold

If the formula holds, you can think that 18 is composed of 1 and 8, and 9 plus 9 equals 18, then this equation is equivalent to 1 + 8 (18) = 9 + 9

Move the decimal point of a decimal one place to the right to get a new number year, and the new number is 25.2 more than the original number. What is the new number?
Explain clearly

Move the decimal point one place to the right, expand 10 times, larger than the original number
10-1 = 9 times
The original number is
25.2÷9＝2.8
The new number is
2.8×10＝28

The speed ratio of the car to the truck is 3:5. The two cars run from two places at the same time and meet at a distance of 15 kilometers from the midpoint. How many kilometers has the truck traveled?
Hurry!

A and B start from a and B at the same time. The first meeting place is 100km away from A. after meeting, the two cars continue to drive at the same speed. After arriving at B and a respectively, they immediately return along the same road. At this time, they meet at 60km away from B

Judging triangle shape (4) acosb + bcosc + ccosa = bcosa + ccosb + acosc
Judging triangle shape (4) acosb + bcosc + ccosa = bcosa + ccosb+

Let a / Sina = B / SINB = C / sinc = k, then a = ksina, B = ksinb, And it's also the case of the case, and the bcoscc and the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C of the C when sin (C-A) is equal to 0, The equation holds, at this time, A-B = 0, B-C = 0, C-A = 0, so a = b = C, so the triangle is an equilateral triangle

The length of train a and train B is 144m and 180m, and train a travels 4m more per second than train B. (1) it takes 9 seconds for the two trains to travel in opposite directions, from meeting to all staggering. What's the speed of the two trains? (2) if they travel in the same direction, how many seconds does it take for the head of train a to overtake train B from the tail of train B to the end of train a

1. The distance between car a and car B is 180m, that is, the length of car B. if the speed of car B is V, then car a is V + 4. So, 180 = 9 * (V + 4) + 9 * v. if v = 8, then the speed of car a is 12 and that of car B is 8

The average number of the five numbers is 40. If the five numbers are arranged from small to large, then the average number of the first three numbers is 34, and the average number of the last three numbers is 45. What is the median of this group of data?

34 × 3 + 45 × 3-40 × 5 = 102 + 135-200 = 237-200 = 37, so the median of this group of data is 37

A and B set out from AB and went opposite each other. When they set out, their speed ratio was 4:3. After the first meeting, a's speed increased by 10%
The speed is reduced by 20%. So when a reaches B, B is still 26 km away from A. so how many km is the distance between AB and B?
(I can't write down the problem, so write it here, don't be surprised)

I'm here purely algebraic
Suppose that the velocity of a is x and the velocity of B is y,
The first meeting took time T1;
therefore
x/y=4/3 …… （1）
s=(x+y)t1 …… （2）
(yt1/1.1x)*0.8y+26=xt1…… （3）
Substituting (1) into (3) and simplifying:
xt1=44
therefore
S=7/4*xt1=77
The distance between the two places is 77km

Prove that the sum of inner angles of convex n-polygon is f (n), f (n) = (n-2) π (n ≥ 3) by mathematical induction

1: 2: suppose that n = K (k is a positive integer and K ≥ 3) is the conclusion. When n = K + 1 (at this time, you can draw a graph by yourself), a new angle ACB protrudes on one side ab of the k-polygon to form a K + 1 polygon

One number is one-third more than one-half, and the other is four-thirds. What is the sum of these two numbers_