solving fractions, please help

Question

The container that holds the water for the football team is 1/2 full. After pouring out 5 gallons of water, it is 3/10

 full. How many gallons can the container hold?

Answer 1

F/2 - 5 = 3F/10

.5F -.3F = 5

.2F = 5

F =25 gallons capacity

after pouring out 5 that leaves 25/2 - 5 = 7.5 gallons

7.5 = .3F

F= 10/3 x 7.5 = 10 x 2.5 = 25 gallons at full capacity