algebra
posted by jim .
show how to solve these problems:
1. 6x  y = 4
2x + 2y = 15 answer:x = 1/2
y = 7
2. x +y = 1 x = 1/3
2x  y = 2 y = 4/3
3. x  y = 3 x = 5/2
6x + 4y = 13 y =  1/2
I just need to know how to solve these problems. Please show me how it is done.

Do them all the same way: either by combining equations in a way that cancels out one unknown, or by substitution.
Here is how problem #3 can be solved:
Substitute y + 3 for x in the second equation,
6(y+3)+ 4y = 13
10y + 18 = 13
10 y = 5
y = 1/2
x = y+3 = 5/2
Now you try the others.