Let x be the unknown amount of child tickets
Let 450 - x be the unknown amount of adult tickets (This is because the total amount subtracted from the child tickets can only be the adult tickets since there are no other tickets)
2x+5(450-x)=1800
(2x because each child ticket cost $2 and same for the adult tickets. Each adult ticket cost $5. So, the sum must be 1800.)
Simplify the equation.
2x+5(450-x)=1800 *Distribute*
2x+2250-5x=1800 *Combine like terms. (2-5=-3)*
-3x + 2250 = 1800 *Move constants and variables to opposite sides*
-2250 -2250
---------------------------
-3x=-450 *Divide by 3 to isolate the variable*
---- ------
-3 -3
x=150
So, there are 150 child tickets. To find adult tickets, just subtract children tickets from the amount of tickets bought (450-150) to get 300 adult tickets sold.