Question 637104
Given:
(1) x/4 + y/3 = 5
(2) x   - y   = 6
Solve by addition.
Multiply both sides of (1) by 3
3*(x/4 + y/3) = 3*(5)
3*(x/4) + 3*(y/3) = 15 yields
(3) 3/4*x + y = 15
Now add (2) + (3)
(1+3/4)*x + (1-1)*y = 6 + 15 which reduces to
7/4*x   + 0*y = 21  or
(4) 7/4*x = 21
    x = (4/7)*21
    x = 84/7
    x = 12
Then using (2)
    y = x - 6
    y = 6
Are these values correct? Let's see.
Put x = 12 and y = 6 into (1)
Is (12/4 + 6/3 = 5)?
Is (3 + 2 = 5)?
Is (5 = 5)? Yes
The answer is x = 12 and y = 6
PS We don't need to check our answer in equation (2) because we used it to derive the value of y.