Let n be unknown number, then 1/5 of this number is 1/5n. When you add these two numbers, you get
\(n+\dfrac{1}{5} n.\)
You know that this sum is equal to 24, so
\(n+\dfrac{1}{5} n=24.\)
1. Multiply this equation by 5:
\(5n+n=120.\)
2. Solve it:
\(6n=120,\
=120:6,\
=20.\)
Answer: n=20, correct choice is B.
