It is 391 because 1+0=1, 9+0=9, and 1+2=3
All you need to do is plug in some x values and find the correspoding y value
when x=0, y=-3
when x=1, y=9
when x=2, y=21
when x=-1, y=-15
It's quite simple when you break it down
20/45 let's divide by 5
4/9
we can't divide anymore, no common denominator. The answer is 4/9