Question 182907
Simplify the following problem 
(-7c^3d^4)(4cd^3)
I got as far as
(-7)4(cc^3)(d^4d^3)
{{{(-7c^3d^4)(4cd^3)}}}
={{{-28c^4d^7}}}
You were almost done.  Just multiply the 4 and 7, and add exponents.