Find the coefficient of `x^5` in the expansioin of the product `(1+2x)^6(1-x)^7dot`

Explanation

We have,


`(1+2 x)^{6}(1-x)^{7} `


`= {[1+\ ^{6} c_{1}(2 x)+\ ^{6} c_{2}(2 x)^{2}+\ ^{6} c_{3}(2 x)^{3}+\ ^{6} c_{4}(2 x)^{4}+\ ^{6} c_{5}(2 x)^{5}+\ ^{6} c_{6}(2 x)^{6}] times[1-7 c_{1} x+7 c_{2} x^{2}-7 c_{3} x^{3}+7 c_{4} x^{4}-7 c_{5} x^{5} cdot ldots] `


`=(1+12 x+60 x^{2}+160 x^{3}+240 x^{4}+192 x^{5}+cdots) `


...