How do you solve this system?

3x - 4y = - 15

4x + 3y = 55

Ok so what you do is for this one, eliminate a variable

so we choose to eliminate the y's

multiply first equation by 3 and multiply second equaiton by 4 and add them

9x-12y=-45

16x+12y=220 +

25x+0y=175

25x=175

divide both sides by 25

x=7

sub back

4x+3y=55

4 (7) + 3y=55

28+3y=55

minus 28 from both sides

3y=27

divide both sides by 3

y=9

x=7

y=9

(x, y)

(7,9)

the solution is (7,9)

You need to try and error which you hve to put 0 to replace x or y

3x - 4y = - 15

3 (0) - 4y = - 15

15 = 4y

y = 3.75

or

3x - 4y = - 15

3x - 4 (0) = - 15

3x = - 15

x = - 5