Billy would have of scored a total of 40 points because then you split 90 in half you get 40 50 and then 50 is 10 more than 40 and logan scored 10 more so here is your answer
um what I do is I go from like if I was doing 12 I would go 1 times 12 and then 2 times 6 and 3 times 4 and then I would stop cause it's repetitive if that makes sense