Solve for both systems: 7z+4x=66 and 4z + 7x = 66

7z+4x=66

7z-7z+4x=66-7z

4x=66-7z

4x/4=66-7z/4

x=16.5-1.75z

4z + 7x = 66

4z + 7(16.5-1.75z) = 66

4z + 7(16.5) (7)(-1.75z) = 66

4z+115.5-12.25z=66

115.5-8.25z=66

115.5-8.25z-115.5=66-115.5

-8.25z=-49.5

-8.25z/-8.25=-49.5/-8.25

z=6

x=16.5-1.75z

x=16.5-1.75(6)

x=16.5-10.5=6