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The speed of car a is 40, and that of car B is 60. The two cars are facing each other from ab. three hours after they meet, car a arrives at B. find the distance between the two places
Let the time from starting to meeting be x, then
40 * 3 = 60 * x (a goes through BC section 40 * 3, B goes through BC Section 60 * x)
X=2
So it takes two hours for a to go through the AC section, so it takes five hours from a to B
40*5=200
The distance between the two places is 200
A and B leave from a and B respectively, and meet at 2.5 o'clock. When they meet, B travels for 105 kilometers, and then continues to drive. After arriving at B and a respectively, a and B drive back immediately. When they meet for the second time, B is 90 kilometers away from a, so as to find the distance between a and B
When B met for the second time, it took 2.5 × 3 = 7.5 (hours) and drove 3 × 105 = 315 km. It is also known that B drove 90 km when turning back from a, so the distance between a and B is 315-90 = 225 (km). A: the distance between a and B is 225 km
A and B leave at the same time. They meet 9 hours later. When they meet, a takes 40% of the whole journey. How many hours does it take B to finish the whole journey?
fast
9/(1-40%)=15
If Party A has driven 40% of the road, that is, 2 / 5, then Party B has driven 3 / 5
B = 15 / 3 / 9
If 2 / 5 is the rest of B's journey, B needs (2 / 5) / (1 / 15) = 6
Then it will take 9 + 6 = 15 hours for B to drive the full distance
B. It takes 15 hours to complete the whole journey
It takes x hours to set up B line
（1-40%）/9=1/x
60%/9 =1/x
60%x =9
x=15
A: it takes 15 hours for Party B to complete the whole journey
If the inequality x + 2 ≥ - 1 has a solution, then the value range of a is 1-2x ＞ x-a
If the inequality x + 2 ≥ - 1, 1-2x ＞ x-a has a solution, then the value range of a is
Because x + 2 ≥ - 1 holds, we get x ≥ - 3
1-2x > x-a leads to x-3 and then to a > - 10
Because 1-2x > x-a
A
3 / 7 minus 8 / 21 + 9 / 14 =?
Simple operation
3/7-8/21+9/14=18/42-16/42+27/42=29/42
A and B set out from a and B at the same time. A rode a bicycle, B drove a car, and drove along the same route at a constant speed. After three hours of departure, they met. It is known that B traveled 90 kilometers more than a when they met, and arrived at a after 1:00. What are the speeds of a and B?
As shown in the figure, let B's speed be x km / h, and the meeting point be C, then BC = x km, AC = x + 90. From: 3x = x + 90, we can get: x = 45. So: A's speed is 453 = 15 km / h, B's speed is 45 km / h. answer: A's speed is 15 km / h, B's speed is 45 km / h
Is the equation [K + 1] X & # 178; + [k-1] x + k = 0 a linear equation with one variable when k is taken
For linear equation with one variable, the coefficient is 0
k+1=0
k=-1
The equation of x [K + 1] X & # 178; + [k-1] x + k = 0 is a linear equation of one variable
Then k = - 1
If the solution set of inequality system (A-1 < x < A + 2) is 3 < x < A + 2, then the value range of a is_____ .（3＜x＜5
The system of inequalities (A-1 < x < A + 2,
3＜x＜5
If the solution set of a is 3 < x < A + 2, then the value range of a is_____ .
According to the nature of inequality, there is the following relation
a-11；a≤4；a≤3
Find the intersection, get 1
What is four minus fourteen
Minus ten
A and B set out from a and B at the same time. A rode a bicycle, B drove a car, and drove along the same route at a constant speed. After three hours, they met. It is known that B traveled 84 kilometers more than a when they met, and B arrived at a after 5 / 4. What are the speeds of a and B?
B finished the whole process
3 + 5 / 4 = 17 / 4 (hours)
When we met, B made the whole journey
1 △ 17 / 4 × 3 = 12 / 17
When they met, a did the whole journey
12 out of 1-17 = 5 out of 17
The whole process is
84 ÷ (12 / 17-5 / 17) = 204 (km)
B. driving every hour
204 △ 17 / 4 = 48 (km)
A every hour
204 × 5 / 17 △ 3 = 20 (km)
3b-3a = 84, 5 / 4 B = 3A, a = 20, B = 48, a and B are the velocities of a and B respectively
&#If the speed of a is x km, then the speed of B is 84 / 3 + X km.
3x=1.25(84/3+x)
3x=1.25(28+x)
3x =35+1.25x
x =20 84/3+20=48
A: A is 20 km, B is 48 km.
Note 1.25 is the result of five fourths.
I wish you a happy study!
Let a be x, B be y, AB distance be s, s = 3 (x + y), 3 (Y-X) = 84; s = (3 + 5 / 4) y, x = 20, y = 48
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