45^10 x 5^20 / 75^15
= ( 3^2 x 5)^10 x 5^20 / ( 3 x 5^2)^15
= 3^20 x 5^10 x 5^20 / 3^15 x 5^30
= 3^5
= 243
p/s : theo mk thì lm như vậy đó
\(\frac{45^{10}.5^{20}}{75^{15}}\)
\(=\frac{5^{10}.9^{10}.5^{20}}{5^{30}.3^{15}}\)
\(=\frac{5^{30}.3^{20}}{5^{30}.3^{15}}\)
\(=3^5=243\)