Question 317207
A+C=100 A=100-C
9A+5C=640
9(100-C)+5C=640
900-9C+5C=640
-4C=640-900
-4C=-260
C=-260/-4
C=65 ANS. FOR THE NUMBER OF CHILDREN.
100-65=35 ADULT TICKETS SOLD.
PROOF:
9*35+65*5=640
315+325=640
640=640