Factoring this down, would leave you with two happy expressions in parantheses. (x+10y)(7x-2y). (AKA Factor out an x and a y to be able to simplify even more.)

we notice that it must be a product of 2 different thingummies so we have ( x+/- y)( x+-/ y) we need to determine the spaces ad signs we know that the signs are different since the end result is negative so fidn the first one 7 factor 7=1 times 7 so we have (1x+/- y)(7x+/- y) factor end -20=-1 and 20 or -2 and 10 or -4 and 5 we want the middle term to be positive so the bigger term must be positive try the ones closest first (x-4y)(7x+5y) multiply out the middles and outers 5xy-28xy is not 68xy try -2 and 10 (x+10y)(7x-2y) multily middles and outers -2xy and 70xy=68xy correct answer is (x+10y)(7x-2y)