Decide has two important structures.
decide + infinitive
decide + on + noun/gerund
examples
They decided to go home early.
Paul decided to buy a PlayStation 4.
Marcia and Nelson have decided to get married.
Marcia and Nelson decided on the colour blue for the
bathroom.
They decided on the date to get married.
My brother decided on getting his hair cut.
Some time phrases don't use these, but the prepositions
depend on the words that follow, not the word decide.
examples
Patrick decided at the last minute.
I will decide in September.
