1. 7x-2y = 5 and -7x + 3y = 4
We add both together :
7x - 2y + (-7x + 3y) = 9.
7x - 2y - 7x + 3y = 9
y = 9.
-> x = (5+2x9)/7 = 23/7 (reverse finding x from the first equation.)
2. 5x + y = 7 and 2x - y = 14
We add both together once again :
5x + y + 2x - y = 21
7x = 21
x=3
-> y = 3 x 2 - 14 = -8 (reverse finding y from the second equation.)
3. 5x - 3y = 32 and 2x + 3y = 10
We add both together :
5x - 3y + 2x + 3y = 42
7x = 42
x = 6
-> y = (10-6 x 2)/3 = -2/3 (reverse finding y from the second equation.)