15x+20y+5z I’m pretty sure
If Bob can paint the fence in 4 hours, then in 1 hour he gets 1/4 of the fence painted. If Sarah can paint the fence in 2.5 hours, then she gets 2/5 of the fence painted in one hour (1/2.5 = 2/5). We add those amounts together and set them equal to 1/x, x being the the total time it will take them to paint the whole fence. 1/4 + 2/5 = 1/x. Find a common denominator first, then add the left side together. 5/20 + 8/20 = 1/x. 13/20 = 1/x. Cross-multiply to get 13x = 20 and x = 1.54 hours, just a bit over an hour and a half.
First, we find the time spent accelerating:
s = ut + 1/2 at²; u = 0
10 = 1/2 5t²
t = 2 seconds
Velocity at point B:
v = u + at; u = 0, a = 5 m/s², t = 2 s
v = (5)(2) = 10 m/s
Now, the same velocity is at C so we find the time decelerating to 0 in CD
v = u + at, v = 0, u = 10 m/s, a = -4 m/s²
0 = 10 - 4t
t = 2.5 seconds
Total time = time(AB) + time(BC) + time(CD)
20 = 2 + time(BC) + 2.5
time(BC) = 15.5 seconds
Distance = velocity x time
BC = 10 x 15.5
= 155 m
Answer:
both are quadrilaterals
Step-by-step explanation:
