Explanation:
Seems like a system of equations
We can let
X = Movie Tickets
Y = Popcorn
3x + 3y = 42.75 <--- algebraic equation
Now to solve it
We know the bags of popcorn cost 5.25 each
3x + 3(5.25) = 42.75
3x + 15.75 = 42.75
Now we can subtract 15.75 from both sides of the equal sign
3x = 27
Lastly, we divide by 3 on both sides
x = 9
So in conclusion, the girls spent $27 on movie tickets and each movie ticket cost $9