Answer:
Hello! A function is easily identified when an x value does not have more than 1 y value. a y value can have as many x values to infinity, but x can only have one y.
Example...
x y
3 5
4 5
1 2
4y - 20.......u need to find a common factor that can go into 4y and 20.....the only common factor is 4. So u can factor that out.....4 goes into 4 one time (but do not forget the y) and 4 goes into 20 five times....4(y - 5)
4(y - 5)...u can also check ur answer by distributing the 4 through the parenthesis and getting 4 * y - 4 * 5 = 4y - 20
I got 65 for my answer. Hope that helps!