102

a)
x^3\cdot x^8=x^{11}
b)
4x^7\cdot8x^{14}=32x^{21}
c)
-x^6\cdot5x^{-5}=-5x
d)
\left(3x\right)^2\cdot\left(-2x\right)^3=9x^2\cdot\left(-6x^3\right)=-54x^5