a) C1:
`8/15` : `2/3` + `7/15` : `2/3`
=`8/15` × `3/2` + `(7)/(15)` × `(3)/(2)`
= `4/5` + `7/10`
= `8/10` + `7/10`
= `15/10` = `3/2`
C2:
`8/15` : `2/3` + `7/15` : `2/3`
=`(8/15 + 7/15)` : `2/3`
= 1 × `3/2`
= `3/2`
b)C1:
`4/9` x `3/5` + `5/9` x `3/5`
= `4/15` + `1/3`
= `4/15` + `5/15`
= `9/15` = `3/5`
C2:
`4/9` x `3/5` + `5/9` x `3/5`
= `(4/9 + 5/9)` × `3/5`
= 1 × `3/5`
= `3/5`
@ximbui
#NOCOPY