Answer:
Toy truck will drive 315 miles since last the tank was filled.
Explanation:
BTW troy truck has tank of capacity = 30 gallons
Since the toy truck is half filled so gas in the tank =

= 15 gallons of gas
Average of the toy truck is given as = 21 miles per gallon
That means in 1 gallon truck travels = 21 miles
Therefore in 15 gallons of gas truck will travel = 21 × 15
= 315 miles
Toy truck will drive 315 miles since last the tank was filled.