Question 95621
A+C=29 A=29-C
20A+13C=510 NOW SUBSTITUTE (29-C) FOR A IN THIS EQUATION 7 SOLVE FOR C
20(29-C)+13C=510
580-20C+13C=510
-7C=510-580
-7C=-70
C=-70/-7
C=10 CHILDREN TICKETS SOLD.
29-10=19 ADULT TICKETS SOLD.
PROOF
20*19=10*13=510
280+130=510
510=510