Question

Jenny purchased 26 magazines for her project research at a total cost of 134$.The art related magazines cost4$ each,while the science related magazines cost 7$ each.Find the number of art related magazines and science related magazines purchased

Answer 1

Assume that
Art magazine = A
Science magazine = S

A + S = 26 
4A + 7S = 134

Use either substitution method or elimination to solve.

personally i would solve using substitution 
in the 1st equation isolate A
A = -S + 26
and then substitute the value of A in the 2nd equation 

4(-S + 26) + 7S = 134
-4S + 104 + 7S = 134
3S + 104 = 134
3S = 30
S = 10

Now find A

A + S = 26
A + 10 = 26
A = 16

Therefore we would have 
10 Science magazines and 16 Arts.