First, how much were her songs? It's two songs each, and their separate prize was 0.99:
total prize was 2*0.99=1.98
this gets added to the membership prize:
19.99+1.98=21.97
you can also calculate this by rounding all the numbers (20+1+1) and substracting the amount you rounded (three times one cent) - the result would be the same.
X-6= units digits
X= tens digit
4(x)+5(x-6)=51
9x-30=51
9x=81, x=9
Plug x back into top equation:
9-6=3, units digit is 3
X=9, tens digit is 9
The two digit number =93
I think it is C but I am not for sure
