Answer: All you possible answer are y=25-15x, y=-15x+25, y=5(-3x+5), and -5(3x-5). Keep in mind that these answers all mean the same thing and have that same value but they are in different forms.
Explanation:
To isolate the y, subtract 15x from both sides of the equation (in order to keep the equation balanced). You should get 15x+y-15x=25-15x. Simplify and your equation will be y=25-15x. It could also be rearranged to be y=-15x+25. If you want to go a step further, you can factor out 5 from -1x and 25 to get y=5(-3x+5). Finally, if you wanted to go even further, you could factor out -5 to get y=-5(3x-5). So all you possible answer are y=25-15x, y=-15x+25, y=5(-3x+5), and -5(3x-5). I don't really know which form you need it in. Hope this helps!