Algebra
posted by Ericka on .
I'm confused regarding the elimination method for
5x  7y = 16,
2x + 8y = 26

#1: 5x  7y = 16
#2: 2x + 8y = 26
To eliminate y, multiply #1 by 8 and #2 by 7 to get
40x  56y = 128
14x + 56y = 182
If you add those two new equations, the y's are eliminated and you get
54x = 54
x=1
Now you can go back and calculate y from one of the original equations. 
5 x  7 y =  16 Multiply both sides by  2
 10 x + 14 y = 32
2 x + 8 y = 26 Multiply both sides by 5
10 x + 40 y = 130
 10 x + 14 y = 32
10 x + 40 y = 130 Add equations
 10 x + 10 x + 14 y + 40 y = 32 + 130
54 y = 162 Divide both sides by 54
y = 162 / 54 = 3
5 x  7 y =  16
5 x  7 * 3 =  16
5 x  21 =  16 Add 21 to both sides
5 x  21 + 21 =  16 + 21
5 x = 5 Divide both sides by 5
x = 1
Solutions :
x = 1 , y = 3