Question

In a sweet shop you can buy packets of mints for 20p each and bars of chocolate for 30p each. The total cost of m packets for mints and c bars of chocolate is given by the formula T=20m +30c

Use this formula to calculate the cost if:

m=2 and c=1
m=8 and c=0

Answer 1

If m = 2 and c = 1, then T = 70
If m = 8 and c = 0, then T = 160

Explanation
Multiply 20 by 2 ~ 20(2) ~ 20m = 40
Multiply 30 by 1 ~ 30(1) ~ 30c = 30
The sum of the two is 70
T = 70

Multiply 20 by 8 ~ 20(8) ~ 20m = 160
Multiply 30 by 0 ~ 30(0) ~ 30c = 0
The sum of the two is 160
T = 160

Answer 2

The first equation answer would be 70, whilst the second equation's answer is 160. I think this would be the correct answer:

20(2) + 30(1) = 70.

20 (8) + 30(0) = 160.

Explanation:

Basically, you would do 20(2) + 30(1) for one of the equations and 20(8) + 30(0) for the other equation. Those equations would give you the answer.