Answer:
Well, I used to get confused about this. The answer by the way is 15y because normally when you get the LCD of denominators in algebraic expressions, you simply multiply them. Here:
[tex]\frac{y + 2}{3y} + \frac{y + 4}{5y} = \frac{5y + 10}{15y} + \frac{3y + 12}{15y}[/tex]
[tex]\frac{5y + 10}{15y} + \frac{3y + 12}{15y} = \frac{8y + 22}{15y}[/tex]
It is just like adding and/or subtracting dissimilar fractions; you get the LCD of both denominators, divide LCD by the original denominators, and multiply their quotient by the original numerators. Then add or subtract the numerators.
