If y is inversely proportional to x, and y= 400 when x= 20, what is the value of y when x= 40 and x= 80?

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.