`Answer:`
`(1.3.5. ... .39)/(21.22.23. ... .40)`
`={(1.3.5. ... .39).(2.4. ... .40)}/{(21.22. ... .40).(2.4. ... .40)}`
`={1.2.3. ... .40}/{(21.22.23. ... .40).(1.2.3. ... .20).2^20}`
`={1.2.3. ... .40}/{(1.2.3. ... .40).2^20}`
`=1/2^20`
`=>{1.3.5...39}/{21.22.23...40=}=1/2^20`
`=>đpcm`
`#Boy`