(2+x)x+(3x+5)x=160
x[(2+x)+(3x+5)]=160
x(2+x+3x+5)=160
x(4x+7)=160
4x^2+7x-160=0
x^2+7x/4-40=0
x^2+7x/4+49/64-49/64-40=0
(x+7/8)^2-2609/64=0
(x+7/8-√2609/8)(x+7/8+√2609/8)=0
x=-7/8+√2609/8或x=-7/8-√2609/8