I am stuck trying to understand how to solve this.

If i have 5320 marbles, and on the first day i remove 3 marbles. Then for each day after i remove +5 more than the previous day. Say day two would i remove 3+5 marbles, 3rd day i remove 8 + 5 marbles.

So how would i go about writing the sequence for this? It doesn't seem like a geometric or an arithmetic sequence since the amount i remove from the total is not a constant, it is increasing by 5 each time..

Additionally how would i go about calculating how many marbles i would have left on the 14th day?