First of all, we have to set variables to represent the given in the problem. We have to set variables for the sales of Tri City and the sales of Solly Company. Hence,
let T be the sales of the Tri City Company and
let S be the sales of the Solly Company
Secondly, we are going to translate into mathematical terms the relationship between the two variables. Hence,
T=4S (1)
T-S=96 (2)
We have two linear equations and two unknowns so this problem is answerable. We substitute equation (1) into equation (2) to give us
4S-S=96
3S=96
S=32
Solving for T gives us
T-32=96
T=96+32
T=128
So, Tri City sold 128 dishwashers while Solly Company sold 32.
