`a ) 5/6 + 7/9 : 5/6 - 1/6`
`= 5/6 + 7/9 × 6/5 - 1/6`
`= 5/6 + 14/15 - 1/6`
`= 25/30 + 28/30 - 5/30`
`= {25 + 28 - 5}/30`
`= 48/30 = 8/5`
`b ) 8/11 × 7/8 + 8/11 : 4/5`
`= 8/11 × 7/8 + 8/11 × 5/4`
`= 8/11 × ( 7/8 + 5/4 )`
`= 8/11 × ( 7/8 + 10/8 )`
`= 8/11 × 17/8`
`= 17/11`
`#dtkc`
