\(a,=\left(1,2\right)^{20}:\left(1,2\right)^{17}=\left(1,2\right)^3=\dfrac{216}{125}\\ b,=\left(-1,25\right)^5\cdot\left(-1,25\right)^4=\left(-1,25\right)^9=\left(-\dfrac{4}{3}\right)^9=...\)
\(a,\left(-1,2\right)^{20}:\left(1,2\right)^{17}=\left(-1,2\right)^3\)
\(b,\left(-1,25\right)^5.\left(1,25\right)^4=\left(-1,25\right)\)