What is 8,5 divided by 0,04

Complete the solution of the equation. find the value of y when x equals to 6 4x+y=20

Can someone me with this? i’m not sure what to put for my equations.

At a local museum, the total price for one adult and one child is $11. mrs. smith paid for herself and her three children. she spent $19. record the system of equations to be solved and then find the price of an adult and child ticket using either elimination or substitution.