9) Solution of 2x - y = 3 and x + 2y = 9 is a) 2,3 b) 4,3 c) 3,3 d) 2,4?

At last! A correctly presented math question!

You have two lines. They look like this: www.wolframalpha.com/input/?i=plot+2x+-+y+%3D+3,+x+%2B+2y+%3D+9

Where they cross, the values of x and y satisfy both equations simultaneously, so it is called a simultaneous system. There are two ways to find that point. Substitution is when you solve one equation for one variable and substitute that into the other equation.

x + 2y = 9 Subtract 2y.
x = -2y + 9 Substitute this for x in the other equation.

2(-2y + 9) - y = 3
-4y + 18 - y = 3
-5y = -15
y = 3 Now put this into either original equation to find x.

x + 2(3) = 9
x = 3

C is the correct answer.

Elimination is when you add the equations in a way to eliminate one variable. Otherwise the process is the same.