First, you try to make sure that both the denominators are the same. In order to do this, you multiply both fractions' numerator and denominator by the other fraction's denominator. Next, you combine like terms in the numerator, and then you simplify the fraction.
Think of PEMDAS, or Please Excuse My Dear Aunt Sally. Which is Parentheses, Exponents, Multiplication and Division, and Addition and Subtraction in that order.
D=2x+2
X=7
Plug in the value for Max's age.
D=2(7)+2
D=14+2
D=16
Max is 7
Dee is 16
20/15=N/27
Do cross multiplication.
20x27=540
540/15=39
So the answer ia 39.
