Question

A music concert was attended by 450 people. Adult tickets sold for $70 and children’s tickets for $40. If total sales were $27,750, how much of each ticket was sold?

Answer 1

A+C=450
70A+40C=27750

multiply first equation by 70
70A+70C=450*70
70A+40C=27750

subtract second equation from first.
30C=27750-450*70

solve for C, then go solve for A
A=450-C