In how many ways can we get $99$ with $1,5,10,25$ (order doesn't matter)? 

I have to do this using combinatorial class. I was thinking about creating one $A = \left \{ a,b,c,d \right \}$ where $\left \|a\right \|=1, \left \|b\right \|=5, \left \|c\right \|=10, \left \|d\right \|=25 $. Then $A(x)=x+x^5+x^{10}+x^{25}$. And now I'm stuck. I can't use $Seq(A)$ here, I mean order doesn't matter, and I'm not so sure how to get the ways of summing from that. I would appreciate if someone could explain that to me.