Question

(b) The cost of buying 5 burgers and 3 drinks is $13.

The cost of buying 3 burgers and 5 drinks is $11.
Find the cost of buying 2 burgers and 2 drinks.

Answer 1

I think James should go vegan ! Anyway the total cost is 6, you have to add up both sides then subtract! -Karen Johnson

Answer 2

Let's denote:

The cost of buying 1 burger: x

The cost of buying 1 drink: y

Then, we have:

5x + 3y = 13 (1)

3x + 5y = 11 (2)

Add up both sides of (1) and (2):

=> 8x + 8y = 24

=> x + y =3 (*)

Subtract both sides of (1) to (2):

2x - 2y = 2

=> x - y = 1 (**)

From (*) and (**):

x = 2

y = 1

=> The cost of buying 2 burgers and 2 drinks: 2(x + y) = 2(2 + 1) = 6$