Question

Not good with word problems please help

Answer 1

Let a and b be the respective rates in bricks per minute for Alex and Bob separately.

Alex lays 4 bricks per minute more than Bob

a = b + 4

Working together, their rates scale by 3/4 and they achieve 15 bricks per minutes.

(3/4)(a + b) = 15

Two equations, two unknowns, we solve:

b = a - 4

(3/4)(a + a - 4) = 15

2a - 4 = (4/3) 15 = 20

2a = 24

a = 12

b = a - 4 = 8

Answer: Alex alone does 12 bricks per minute, Bob alone 8 bricks per minute

Check:  a=b+4, good

(3/4)(12 +8)=(3/4)(20)=15, good