3 c^3 ( 5 c + 2 c^ )
Eme, something is missing in the expression you wrote above. In any case, let's assume that we had
3c3(5c+2cq) where q is any integer (or even just any real number as a matter of fact). Then you would have
3c3*5c + 3c3*2cq where we used the distributive property of multiplication with respect to addition.
Now each term in the addition is a monomial and all you have to do is multiplying the numeric coefficient and compute the exponents of the letteral, c, by applying the rule cn*cm=cn+m. Thus we find
15c3+1 +6c3+q = 15c4+6c3+q.
To solve your given assignment, just replace q with the proper value given in the text of your problem and that you forgot to include in the expression at the top.