Question

Mal bought 3 bottles of milk and 4 bags of chips for a total of $17. At the same shop, Barbara bought 1 bottle of milk and 5 bags of chips for $13.
Find how much each bottle of milk and each bag of chips cost by completing the following steps:
a) Define two variables to represent the problem.
b) Write a pair of simultaneous equations relating to the two variables.
c) Solve the pair of equations using substitution or elimination.
d) Write your answer in words.

For me, I only know how to answer a) and b) which is:
a) Let $m be the milk, Let $c be the chips
b) 3m + 4c = 17
m + 5c = 13

Answer 1

one comment, on b: you need to be specific $m is bottles of milk, $c is bags of chips.
c. 3m + 4c = 17
m + 5c = 13
multiply second equation by -3, then add the equations.
4c-15c=17-3*12
solve for c. then put c into either equation, and solve for m

Answer 2

For D just write what this person has given you in words.