In the expansion of the term is given by

(a)

, term in x^3

=(x^2+2x+1) (2-3x)^7

For (a)

For getting x^3 the degree of x in second term should be one

(see the formula above)

Hence

in

eliminate x to get value of coefficient

Go ahead with the b and c other terms

2)

(b) , term in x^2 .

If you understood 1 you can do it tell incase if you get stuck again