Form 1 Mathematics Problems... AKA ALGEBRAIC EXPRESSIONS!

[gamegoodc]

1st and 2nd qstion is form1 qstion?=.=
and 3rd question ans is wat they write~
Siti=2h
Her bro=2h+7
Total age=2h+2h+7
=4h+7
jus write like this , sure full marks ~!!
but me sure write in shortcut~