Translation of "to double" into Norwegian

How'd you like to double that and save yourself time and trouble?

Hva med å tjene det doble og spare deg for bryderiet?

My supervisor promised to double my salary if I stayed with the company.

Sjefen min lovte å doble lønnen min hvis jeg ville bli i firmaet.

By agreeing to double the admission fees and split the money between them.

Ved å bli enige om å fordoble inngangspengene og dele beløpet mellom seg.