`5^20 : ( 5^15 . 6 + 5^15 . 19 )`
`= {5^20}/{5^15 . ( 6 + 19 )`
`= {5^20}/{5^15 . 25}`
`= {5^20}/{5^15 . 5^2}`
`= {5^20}/{5^17}`
`= 5^3`
`---`
`( 2^9 . 16 + 2^9 . 34 ) : 2^10`
`= {512 . ( 16 + 34)}/{1024}`
`= {512 . 50}/{1024}`
`= {25600}/1024`
`= 25`
`#dtkc`