First:
2x + 2z = 4
2(x+z)=4
x+z=4/2
x=2-z
-x - y - z= -8
-(2-z)-y-z= -8 replace x
-2+z-y-z= -8 (cancel z)
-2-y= -8
6 = y
Then:
-4x + 4y + 5z = 7 replace x and y
-4(2-z)+4*6 + 5z = 7
-8 + 4z + 24 + 5z = 7
16 + 9z = 7
9z = 7 - 16
9z = -9
z = -9/9
z= -1
Finally
x= 2-z replace z
x = 2- (-1)
x = 3
6^9 x 6^-7 = 6^2
x= -7
Hope this helps :)
5x + 3y = 460
5(x + y = 120)
5x + 5y = 600
Use elimination subtraction
-2y = -140
y = 70
There are 70 student tickets
12-x(5-4k)=y
12-y=x(5-4k)
12-y/(5-4k)=x
