How can I sum up values within Google Sheet cells under a specific condition?

Question

I want to create a Google Sheet that automatically sums up some values. For each green tick in a Present? cell $15 should be added to Total Sum, for each red x nothing should be added. So that all I have to do is fill in presence and the total sum will be calculated.

Date	Present?	money added	Total Sum
1/1/21	✅	+ $15	$15
1/2/21	❌	+ $0	$15
1/3/21	✅	+ $15	$30
1/4/21	❌	+ $0	$30
...	....	...	...
2/24/21	❌	+ $0	$300 (example)

My idea: I need some if condition like =IF( *Present cell* is ✅, then *money added cell* is $15, if not then *money added cell* is 0) and for Total Sum I just need to build the Sum over the whole money added column to get the interim values up until the present date.

Answer 1

Suppose that Date is column A, that Present? is column B etc.

Cell D2 would be:

=IF(B2 = "✅", C2, 0)

And cell D3 would be:

=IF(B3 = "✅", D2+C3, D2)

Repeat D3 until bottom of dataset.

Example.