6/10+9/10= 15/10 how do i reduce it to make it in lower terms?

If you could answer these your a life saver

What is the value of f(x) = 2.2 for f(-2)?

Isabel graphed the following system of equations. 2x – y = 6 y = -3x + 4 she came up with the solution (2,-2). what were the 3 steps she did to get that solution? (make sure they are in the correct order)