The sum of the ages of father and son is 45, and the father is four times as old as the son. How old are you,

The sum of the ages of father and son is 45, and the father is four times as old as the son. How old are you,

45 / [4 + 1] = 9 [years old] children, father 9 * 4 = 36 years old

There are three continuous natural numbers, the smallest of which can be divided by 15, the middle by 17, and the largest by 19______ 、______ 、______ ．

Because the least common multiple of 15, 17 and 19 is 15 × 17 × 19 = 4845, 4845 + 15 = 4860 can be divisible by 15, 4845 + 17 = 4862 can be divisible by 17, 4845 + 19 = 4864 can be divisible by 19, so 4860, 4862 and 4864 can be divisible by 15, 17 and 19 respectively

Root 5 times the square of X - (5 root 2 + 1) x + root 10 = 0

(root 5 times X - 1) times (x - root 10) = 0
The solution X1 = 1 / radical 5, X2 = radical 10

There are 3400 tons of chemical fertilizer in the warehouse, 1 / 4 of which will be transported in the first time and 3 / 10 in the second time. How many tons of chemical fertilizer are there?

3400 * (1-1 / 4) * (1-3 / 10) = 1785 (tons)

Simple calculation of 8 / 9 △ 7 / 4 △ 1 / 3

8/9÷7/4÷1/3
=8/9÷(7/4×1/3)
=8/9÷7/12
=8/9×12/7
=32/21
I'm glad to answer for you, the 1900 team will answer for you
Please click the [select as satisfactory answer] button below

An applied problem of first degree inequality of one variable in elementary two
Xiaobao and her parents play on the seesaw. Her father weighs 72kg. Sitting on one side of the seesaw, she weighs only as much as her mother. Xiaobao and her mother are sitting on the other side. At this time, her father is still on the ground. Xiaobao puts a 6kg stone on her and her mother's side. Her father is sledged. Xiaobao's weight

Let the weight of Xiaobao be X
Then the meaning of the title can be known
x+2x72
22

1. Li Gang leaves home for work every morning, and Uncle Zhang goes out for a walk every morning. Every day they face each other and meet on time on the way. One day, Li Gang goes out ahead of time, so he meets Uncle Zhang 7 minutes earlier than usual. It is known that Li Gang's speed is 70 meters per minute, and Uncle Zhang's speed is 40 meters per minute. How many minutes does Li Gang go out earlier than usual?
2. Party A and Party B start from a and B at the same time and walk towards each other. The speed of Party B is two-thirds of that of Party A. after they meet each other, they continue to March. When Party A arrives at place B and Party B arrives at place a, they immediately return. It is known that the place where they meet for the second time is 20 kilometers away from the point where they first meet. How many kilometers is the distance between a and B?

1. Uncle Zhang walked 7 minutes less, 7 * 40 = 280 meters less, Li Gang walked 280 meters more than usual, 280 / 70 = 4 minutes more, Li Gang went out 4 minutes earlier than usual
2. In the first meeting, Party A walked 3 / 5, and Party B walked 2 / 5. From the first meeting to the second meeting, Party A and Party B walked twice as long as the first meeting, so from the first meeting to the second meeting, Party B walked 2 * 2 / 5 = 4 / 5, so the location of the second meeting is 2 / 5 + 4 / 5-1 = 1 / 5 from a, and the location of the first meeting is 3 / 5 from a, so the distance between a and B is 20 / (3 / 5-1 / 5) = 50 km

How to multiply (0.75 minus 3 / 16) by (2 / 9 plus 2 / 3)

(0.75 minus 3 / 16) times (2 / 9 plus 2 / 3)
=(3/4-3/16)(2/9+2/3)
=(12/16-3/16)(2/9+6/9)
=9/16*8/9
=1/2

The original price of Andersen's fairy tales is 24 yuan. The current price is 1 / 6 lower than the original price. How much cheaper is the current price?

Take the original price as unit 1, the current price is 1 minus 1 / 6, which is 5 / 6. Multiply 24 yuan by 5 / 6, which is 20 yuan. This is the current price. 24-20 = 4 yuan. The current price is 4 yuan cheaper than the original price

2 + 3 + 4 + 5 + 6 + 8 + 1 + 7 + 9 + 10 + 20 + 30 + 40 + 50 + 60 + 70 + 80 + 90, the first correct answer is to adopt

495