I would write systems of equations for this problem.
1.5x + 4y = 5050
x + y = 2200
From there solve the system of equations where x represents the number of children and y represent the number of adults.
x + y = 2200
x = 2200 - y
Plug "x" into the other system of equation.
1.5(2200-y) + 4y = 5050
3300 - 1.5y + 4y = 5050
2.5y = 1750
y = 700
Since you have the value for y, solve for x.
x + y = 2200
x + 700 = 2200
x = 1500
So, the solution is: 1500 children and 700 adults attended.
Just to check our answers:
1.5x + 4y = 5050
1.5(1500) + 4(700) = 5050
2250 + 2800 = 5050
5050 = 5050