How to calculate the sum of values contained in alternating columns using a formula that includes the CHOOSECOLS function.

I am just learning the possibilities of Excel in doing basketball stats. I input all the stats on one sheet and then have a summary of them on another with totals and percentages etc.

I know there are lots of stats sheets already premade but, as this is for younger kids, the stats need to be a bit more specific to assist the coach to notice trends of strengths and areas that need development. I've got most of it worked out but I can't seem to get the free throws section to work.

Basically, I have a column which shows the free throws awarded - labelled A, then, next to it a column that shows the shots made (it could be 0 to 3 depending) labelled M. I want the summary sheet to add together all of the values in the A columns. Next to it will be all the sum of all the values in the M column and, next to that will be the FT% which will divide the value of M / A

I've attached screenshots of what the sheets look like and the formula that I tried but doesn't work.

Any help would be appreciated.

Summary Sheet

Input Sheet