2)(7a^5b^2c) (-3ab^4c)
4) (-3/2a^3xy^3) (3/4ax^2y)

2) (7*(a^5b)^2c)*(-3ab^4c)

(7a^10bc)*(-3ab^4c)

=-21a^10bc+1 b ^4c

4) ((-3/2a)^2*3xy^3)*(3/4ax)^2y

(9/4a^2*3xy^3)*9y/16^y*a^2yx^2y

27xy^3/4a^2*9y/16^y*a^2yx^2y

27y^3/4a^2*9^y/16^y*a^2yx^2y-1

27y^3*9^y/4a^2y+2 *16^y+x^2y-1

3^3y^3*3^2y/4a^2y+2 *4^2y*x^2y-1

=3^2y+3 *y^3/4^2y+1 *a^2y+2 x^2y-1