4 x + 6 y = 1 / 8
-
3 x + 7 y = 1 / 10
_________________________
x - y = 1 / 8 - 1 / 10
x - y = 5 / 40 - 4 / 40
x - y = 1 / 40 Add y to both sides
x - y + y = 1 / 40 + y
x = y + 1 / 40
4 x + 6 y = 1 / 8
4 ( y + 1 / 40 ) + 6 y = 1 /8
4 y + 4 / 40 + 6 y = 1 / 8
10 y + 1 / 10 = 1 / 8 Subtract 1 / 10 to both sides
10 y + 1 / 10 - 1 / 10 = 1 / 8 - 1 / 10
10 y = 5 / 40 - 40 / 40
10 y = 1 / 40 Dvide both sides by 10
y = 1 / 400
x = y + 1 / 40
x = 1 / 400 + 1 / 40
x = 1 / 400 + 10 / 400
x = 11 / 400
Solutions :
x = 11 / 400
y = 1 / 400
Proof :
3 x + 7 y = 1 / 10
3 * 11 / 400 + 7 * 1 / 400 = 1 / 10
33 / 400 + 7 / 400 = 1 / 10
40 / 400 = 1 / 10
1 / 10 = 1 / 10
solve:
4x + 6y = 1/8 and 3x + 7y = 1/10
1 answer
1 answer