To solve this, we will use the Distributive Property. An easy way to remember how to do these problems is the acronym F.O.I.L. This acronym tells which numbers in the parentheses you should multiply. It stands for:
First
Outside
Inside
Last
Using this acronym, let's begin to solve.
(y-15)(y-8)
First: y*y=y²
Outside: y*-8=-8y
Inside: -15*y=-15y
Last: -15*-8=120
Now, we need to simplify our answer by combining the like-terms.
y²-8y-15y+120
y²-23y+120
That's it! The solution to this problem is y²-23y+120.