Question 170899
Solve for x and y:
8x + 2y = 7
3x - 4y = 5 
:
There are two ways to solve these, elimination and substitution. 
Elimination:
You multiply one or both equations so when the equations are added or subtracted, one of the variables is eliminated. Then it is easy to solve for the other variable:
:
Multiply the 1st equation by 2 and you have:
16x + 4y = 14
 3x - 4y = 5
----------------Adding will eliminate y:
19x + 0y = 19
or
19x = 19
x = {{{19/19}}}
x = 1
:
Now substitute 1 for x in one of the original equations, we'll use the 1st one.
8(1) + 2y = 7
8 + 2y = 7
2y = 7 - 8; subtracted 8 from both sides
2y = -1
y = {{{-1/2}}}
:
Check solutions by substituting both solutions in the 2nd original equation.
3(1) - 4(-1/2) = 5
3 + 2 = 5; remember minus a minus is a plus
:
Did this help you understand these problems?