Question

Dump Truck #1 is traveling east at 50 mph and is 20 miles ahead of Dump Truck #2, which is following behind it at a speed of 70 mph. How many hours will it be before they are side-by- side?​

Answer 1

Explanation:

Formulas

d1 = 20 + 50*t This is dump truck #1

d2 = 70*t This is dump truck #2

d1 = d2 This is given in the problem

Solution

if d1 = d2 then you get 20+50t = 70t as your working equation.

20 + 50t = 70t Subtract 50t from both sides

20 +50t-50t = 70t-50t Combine

20 = 20t Divide both sides by 20

20/20 = 20t/20

1 = t

Answer

after 1 hour Dump Truck 2 will catch dump truck 1