so john is x and if Maya has the same as john but -3 then
x+x-3
but sam is still missing and she has half of Maya which is 0.5x - 1.5
so the equation is
x+x-3+0.5x-1.5=68
and then you add 3 and 1.5 to 68 which is
2.5x=72.5
and you divide by 2.5 which is 29
John has 29 points