Add: b^−3 ca^−1 −xc^−2

how would i do this ?

Let me make sure I have the question right. We have
b^(−3) ca(^−1) −xc^(−2 )=?
You might also write this as
(1/b^3) c(1/a) − x(1/c)=
c/(a*b^3) - x/c=?
If this is correct, then find a common denominator and do the subtraction. If I got the question wrong then repost it.

hhh