Find the total amount of money that Jeff will have in his savings account after 3 months if his initial deposit was $945 with a 4.5% interest rate.

I have no idea what the answer is. Please explain.

You are probably working with "simple interest"

Interest = Principal x rate x time
= 945*.045*3/12
= 10.63

So he will have $945 + $10.63
= $955.63