Answer:
1/10
Explanation:
Begin by writing the given phrase as an equation. The sum of two-fifths and f can be written 2/5+f, and that term is equal to one-half, written 1/2. Written together,
2/5+f=1/2.
Begin by subtracting 25 from each side,
2/5+f−2/5=1/2−2/5.
Simplify and rewrite with a common denominator,
f=1/2⋅5/5−2/5⋅2/2
and simplify again,
f=5−4/10,
and solve for f,
f=110.