Question

At a fast-food joint, 2 cheeseburgers and 3 medium shakes cost $8.98. At the same fast food joint, 7 cheeseburgers and 2 medium shakes cost $15.45. What is the cost of a cheeseburger? What is the cost of a medium shake?

Answer 1

Lets say cost of cheeseburgers is x and cost of medium shake is y

so first fast food joint gives 2x+3y=8.98----------1
and nother one gives 7x+2y=15.45-----------------------2

multiply  eq1 with 2
and multiply 3 to eq3
4x+6y=17.96
21x+6y=46.35
subtract both eq

-17x= - 28.39

cheese burger cost x=1.67 $ put x in eq1
medium shake cost y=1.88$