Question

A team won 3 of their first 10 games. If they win the next n games, they will have won 50% of their games. What is the value of n?

Answer 1

If the team wins the next n games, the number of games they win becomes 3 + n. The total number of games is 10 + n. The ratio of games won over total number of games would be 1/2. 
                       (3 + n) / (10 + n) = 1/2
From the equation, the value of n is 4. 

Answer 2

50%=50/100=1/2

$\frac{3+n}{10+n}$=$\frac{1}{2}$
solve
multiply both sides by  (2)(10+n)
(2)(3+n)=(1)(10+n)
6+2n=10+n
minus n from both sides
6+n=10
minus 6 from both sides
n=4

answer is n=4