I believe the first one is 210
The party on Saturday was bigger. You know that Friday they had 31 people. Saturday they had 210 people.
The first one is 1+2(15)=31
The second one I’m not sure how to write up an equation for that because I just added 1+2+3+4+5..... and so on until 20 and got 210.
Not even sure if this is even right honestly, Just thought I’d at least try and help.