57 children tickets were sold on Saturday.
You could set this up as a system of equations.
x + y = 155
6.00x + 9.90y = 1312.20
First step is multiplying the first equation by -6 to use the elimination method.
-6.00x + -6.00y = -930
6.00x + 9.90y = 1312.20
The positive and negative 6x cancel out until you are only left with the y.
Combining them would make your equation...
3.9y = 382.2
Next you would divide by 3.9 on both sides to get the y by itself.
The result of that would be y = 98. Which means 98 adult tickets were sold. Then you would plug y into either of the equations to solve for x.
200.7 I hope this is the answer
16 because 5 times 4 = 20 there for you multiply 4 times 4 to get 16