3p+3q=15 2p+5q=14

3p + 3q = 15        ...(1)

2p + 5q = 14        ...(2)

 

Divide the first equation by 3

p + q = 5

Rewrite this as q = 5 - p   ...(3)

Substitute this into (2)

2p + 5(5 - p)  = 14

Multiply out the bracketed term

2p + 25 - 5p = 14

Collect the p's and subtract 25 from both sides

-3p = -11

Divide by -3

p = 11/3

 

Substitute this into (3)

q = 5 - 11/3

q = 4/3