There's more than one way to combine them really
but an obvious one will be
$2,234.38 after 5 years and he will have to repay $9,384.38.
Need some more info, what are the dimensions of the bricks?
The rockets rate of change in miles per second is:
(5 - 1)/(2.5*60 - 30) = 1/30 miler per second or 0.033
the rockets rate of change in miles per minute is:
(5 - 1)/(2.5 - 30/60) = 2 miles per minute
486/6=81
Square root 81 = one side length = 9m
volume = 9^3 = 729