Hey everybody, i really need some help quick.

Im having trouble with linear equations. If anyone can show me how to solve them that would be great.

3x + 5y = 26

2x - y = 13

x - 2y = -12

3x + 8y = 34

I also need help on these.

2x - 3y = 4

.02x + .01y = .52

Last but not least...

Terry did all 25 problems on the test and got an 85. Scores are computed by giving 4 points for each right answer and subtracting 1 point for each wrong answer. How many problems did Terry get right and wrong?

Varibles:

Equation: