exam Maths Puzzle Numerical Ability

Please, please help? I need to solve:

by addition: 5x - 3y = 13 4x - 3y = 11

by graphing:x - y = 5
x + y = -1

Read Solution (Total 0)

exam Other Question

This is a last Subsitution question, but this one says solve by either ;addition or subtraction.

The problem is:
12a-5b=18
15a-5b=30

Please and Thank You=) how can I simplify this radical expression
(sqrt3+5)(sqrt3-3)