Y=2x y is the amount of money made from the sold books x is the number of books that are sold (it is x because you don't know how many will be sold, so you have to account for all possibilities) 2x is because every book is sold for 2 dollars, so that mean x is multiplied by 2 to get y
An equation is: 2(x+3)-7=9 Distribute the 2 2(x)+2(3) -7=9 2x+6-7=9 Combine like terms 2x-1=9 Add one to both sides 2x-1+1=9+1 2x=10 Divide both sides by two to isolate the variable. 2x/2=10/2 x=m
