Explanation:
josh is 1.5 inches taller than sean
so, let sean's height be x
sean = x
josh = x + 1.5
each year josh gain 2.75 inches, and now he's 13 so how many year has passed
13 y - 5 y = 8
then how tall he grew
2.75×8=22
x + 1.5+22=63
x=63-22-1.5
x=39.5