Question

Help plz I'm desperate ​

Answer 1

Anna:

1st month = 18 +
`(3)/(4)` = 18
`(3)/(4)` inches

2nd month = 18
`(3)/(4)` +
`(3)/(4)` = 19
`(1)/(2)`

3rd month = 19
`(1)/(2)` +
`(3)/(4)` = 20
`(1)/(4)`

4th month = 20
`(1)/(4)` +
`(3)/(4)` = 21

5th month = 21 +
`(3)/(4)` = 21
`(3)/(4)`

Grace:

Because Anna is
`(9)/(4)` inches shorter than Grace, we can start the count from the third month:

1st month = 20
`(1)/(4)`

2nd month = 21

3rd month = 21
`(3)/(4)`

4th month = 21
`(3)/(4)` +
`(3)/(4)` = 22
`(1)/(2)`

5th month = 22
`(1)/(2)` +
`(3)/(4)` = 23