GUYS I NEED HELP AND FAST WHATS 9 + 10 !??!??!?!?!??!?!
I PUT 910 BUT GOT IT WRONG PLEASE HELP, IS IT 21, 91, OR 19

For the rule of 78, for a 12-month period, the last term in the sequence is 12 and the series sums to 78. for an 10 month period, the last term is and the series sum is . for a 15 month period, the last term is and the series sum is . for a 20 month period, the last term is and the series sum is

The ratio of the measures of the three angles in a triangle is 2: 9: 4. find the measures of the angels

Which best describes a central bank's primary goals? limiting inflation and reducing unemployment reducing unemployment and maintaining cash flow controlling stagflation and reducing unemployment managing credit and ensuring the money supply's liquidity