Answer:
Step-by-step explanation:
Formulas
d1 = 20 + 50*t            This is dump truck #1
d2 = 70*t                This is dump truck #2
d1 = d2 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 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 Â Â Â Â Â Â Â Â Â Â Â
1 = t
Answer
after 1 hour Dump Truck 2 will catch dump truck 1