Simply the unknowns variables

5(2-c)=10(2c-4)-6(3c+1)

1.25y-20.5=0.5y-11.5

(3) 7p-3q=23(3)

10-5c = 20c-40-18c-6

-5c-20c+18c = -40-6-10
-7c = -56
C = 8.

1.25y-.5y = -11.5+20.5
0.75y = 9
Y = 12

Divide both sides by 3:
7p-3q = 23.