To find the difference between (6x-7y) and (4x+3y) would be by subtracting both the equations. To start, first set up an expression:
(6x-7y)-(4x+3y)
When done, subtract any like terms and add the remaing together:
(6x-4x) +(-7y-3y)
This will result in your answer, 2x-10y
