`a) y × 2/5 = 5/12 + 1/4`
`y × 2/5 = 2/3`
`y = 2/3 : 2/5`
`y = 5/3`
`b) y : 3/7 = 13/15 - 2/5`
`y : 7/3 = 7/15`
`y = 7/15 × 7/3`
`y = /5`
`c) 5/3 - y = 7/12 : 5/6`
`5/3 - y = 7/10`
`y = 5/3 - 7/10`
`y = 29/30`
`d) 4/15 : y = (5/4 + 1/2) × 4/13`
`4/15 : y = 7/4 × 4/13`
`4/15 : y = 7/13`
`y = 4/15 : 7/13`
`y = 52/105`