Question 131792
4a+12c=92
a=2c+3 
4(2c+3)+12c=92
8c+12+12c=92
20c=92-12
20c=80
c=80/20
c=4 compact disks were bought.
a=2*4+3
a=8+3
a=11 audio cassetts were bought.
proof
4*11+12*4=92
44+48=92
92=92