Answer:
21
Explanation:
2.8 for 8 means a ratio of
2.8/8
now we need to transform this ratio to show x/60.
for that we need to multiply the numerator and the denominator with the same factor.
which factor ?
well, the one turning 8 into 60.
so,
8×f = 60
f = 60/8 = 15/2 = 7.5
so,
x = 2.8 × 7.5 = 21
he will need 22 gains for 60 doors.