Answer:3 $,9$,36$
Step-by-step explanation:
Since he bought a cup of plain coffee which costs 1$ and he is carrying 4$ with him he has saved 3$ he would have used to buy a latte.If he does it continously for 3 times a week his saving per day i.e 3$ ×3,a month which is 3$×3(for a week)×4week which makes a month which is 32$.So the answers are 3$,9$ and 36$