I dont understand how to solve a+5

Which of these choices show a pair of equivalent expressions?

Determine the fraction of total interest owed. after the fourth month of a 12-month loan: the numerator is: {(n + ) + (n + ) + (n + ) + (n + )} = , and the denominator is: {(n) + (n + 1) + + (n + )} = . therefore, the fraction is numerator/denominator (to the nearest tenth) =

Complete the solution of the equation. find the value of y when x equals to 6 4x+y=20