The greatest common factor means the expression that goes in to both, so we can work on each term individually.
Firstly, the greatest common factor of 15 and -20 would be 5, because 5 × 3 = 15 and 5 × -4 = -20. This means 5 would be the value in front of x.
Next we have the greatest common factor of x³ and x², which would be x².
Now we have y³ and y, so the greatest common factor is y. I know it gives you an option to put an exponent to y, but you can put 1 there as anything to the power of 1 is itself.
So your final answer is 5x²y¹
I hope this helps!
