Solution:
we are given that
Airplane has a wingspan of 15 feet.
we have been asked to find the wingspan of a model of the airplane, in inches, if the scale factor is 1:60 .
It mean for each one unit of original wingspan we are supposed to have
times the wingspan of model airplane.
Here the original airplane has a wingspan of 15 feet. So the model airplane has a wingspan of

Since one fit=12 inches So we can say

Hence the model airplane has a wingspan of 3 inches.