Answer:
210 adult tickets were sold
Step-by-step explanation:
let x be the number of adult tickets sold
let y be the number of children tickets sold
x+y=260 equation 1
9x+5y=2140 equation 2
multiply equation 1 by 5
multiply equation 2 by 1
5x+5y=1300
9x+5y=2140
subtract equation 1 from 2
4x=840
x=840/4 =210 tickets
substitute for x in equation 1
210+y=260
y=260-210=50
