Barry has three bills to pay. The first bill is three times the amount of the second one. The third bill is ten times the amount of the second bill. The difference between the first bill and the third bill is $1050. What is the total of the three bills?
Both the first and the third are given in terms of the 2nd, so we will let the second be our base variable
let the 2nd be x
then the first is 3x
and the third is 10x
10x - 3x = 1050
7x = 1050
x = 150
sub back into my definitions and add them up