a: x=1/12+4/9=3/36+16/36=19/36
b: x=4/5-3/7=28/35-15/35=13/35
c: x=5/22:3/11=5/22x11/3=55/66=5/6
` x - 4/9 = 1/12`
` x = 1/12 + 4/9`
` x = 19/36`
` 3/7 + x = 4/5`
` x = 4/5 - 3/7`
` x= 13/35`
` 3/11 xx x = 5/22`
` x = 5/22 : 3/11`
` x = 5/22 xx 11/3`
` x= 5/6`
` x : 5/7 = 3/5`
` x = 3/5 xx 5/7`
` x= 3/7`
`x-4/9=1/12`
`x=1/12+4/9`
`x=57/108=19/36`
`b)3/7+x=4/5`
`x=4/5-3/7`
`x=13/35`
`c)3/11xx x =5/22`
`x =5/22:3/11`
`x=5/6`
`d)x:5/7=3/5`
`x=3/5×5/7`
`x=3/7`