Answer:
If 2.5 gallons of paint are needed for the entire fence, then for 1/5 of the fence we need:
2.5 gallons / 5 = 0.5 gallons
To find how much paint is needed for 3/5 of the fence, we can multiply 0.5 gallons by 3:
0.5 gallons * 3 = 1.5 gallons
Therefore, 1.5 gallons of paint are needed for 3/5 of the fence.