Depends on where you are in the math book but this would be the most simple way.
n= number
sqar(-1) = i
Answer is 28 inches.
A square has equal sides and to find the perimeter, you add all the sides.
7 x 4 = 28
Answer: (27, 9)
Multiply the original coordinates by the scale factor 3 to get this answer
9*3 = 27
3*3 = 9
This only works if the center of dilation is the origin.
The general rule is
where k is the scale factor.
It will take him 30 hours
The answer is b I hope I could help