I just solved it and I'm pretty sure its only one solution, I took the bottom equation multiplied it by -3 then i canceled out the equations and got 9. So that would make it C.
It's C.
multiply by 3
x = 4, y = 4x3 = 12
x = 5, y = 5x3 =15
x = 6, y = 6x3 =18
What are you solving for???
So P stands for principle which is the amount of the original investment, R stands for rate which is the percent but must be turned into a decimal, T stands for time for example if the time was in a certain amount of months then you plug that in with x/12, and lastly I stands for interest which is the original investment outcome ^_^