v * t=120
(v-20)(3.5-t) = 120
t = 120/v
(v-20)(3.5- 120/v) = 120
3.5 v - 70 - 120 +2400/v = 120
3.5 v^2 - 310 v + 2400 = 0
v = 80 or 8.57
if v = 80
t = 1.5 hours
v = 8.57 does not work
If a truck travels at 120km to a warehouse with an empty truck. On the return trip, with a full truck, the truck driver travels 20 km slower. If the entire trip took 3.5 hours then determine his speed to the warehouse.
IF the rate is 120 when leaving
and 120-20 is the rate when returning.
1 answer
1 answer