a) \(9^{21}.9^{33}=9^{21+33}=9^{54}\)
b) \(19^{11}.19.19=19^{11+1+1}=19^{13}\)
c) \(25^2.5^2.125=5^4.5^2.5^3=5^{4+2+3}=5^9\)
d) \(t^{2021}.t^2.\left(t^2\right)^2=t^{2021}.t^2.t^4=t^{2021+2+4}=t^{2027}\)
e) \(123^{14}:123^{13}=123^{14-13}=123\)
f) \(64^2:8^3=\left(8^2\right)^2:8^3=8^4:8^3=8^{4-3}=8=2^3\)
g) \(6^{10}:6^3:36=6^{10}:6^3:6^2=6^{10-3-2}=6^5\)
h) \(m^{20}:m^{10}.m^{10}=m^{20-10+10}=m^{20}\)