Write an equivalent ratio for 7 to 9?

Hello people, i have a math question that i need with, me, i will give the correct one brainiest, and for the other correct people, a and 5 stars.

Solve the following pair of equations for x and y: ax/b_ by /a= a +b; ax - by = 2ab

If you double the input of a function and it results in half the output, and if you triple the input and it results in a third of the output, what can be guessed about the function? check all that apply.