Well, I have an example that might help:
Rico's MP3 player holds songs of three different genres: grindcore, zydeco, and kuduro. There are 55 times as many grindcore tracks as there are zydeco tracks, and there are 77 times as many kuduro tracks as there are zydeco tracks. Let xx represent the number of zydeco tracks. Write an expression for the total number of tracks on the MP3 player, and simplify it.
Multiply the number of zydeco tracks by 55 to get the number of grindcore tracks.
5x5x
Multiply the number of zydeco tracks by 77 to get the number of kuduro tracks.
7x7x
Add up the numbers of all the tracks.
x+5x+7xx+5x+7x
Simplify using the distributive property.
=(1+5+7)x=13x=(1+5+7)x=13x
So, Rico's MP3 player holds 13x13x tracks.
I hope I helped you!