Answer: 
Step-by-step explanation:
21 fence posts. i dont know how to draw a picture on this site, but you covert 16in to ft and then divide 32 by 1.5
The idea of grouping is to get the terms in groups that allow you to factor out from each group something that becomes a factor in itself, leaving two factors behind that are alike. Like this: rearrange those terms so they are in this order:
(-70y^2 - 63xy) + (90x^3 + 100yx^2). Now out of the first set we are going to factor out a -7y, and out of the second set we are going to factor out a 10x^2. When we do this, this is what we get: -7y(10y + 9x) + 10x^2(9x + 10y). As you can see, what's inside both sets of parenthesis is the same, just in a different order. We can factor that out now, leaving (9x + 10y)(10x^2 - 7y). And that is factored by grouping.
