there are 25 balls which are red , blue or green . if 8 balls are blue and the sum of green balls and blue balls is less than 17 , at most how many green balls are there ?
"r + g + b = 25 b = 8 b + g < 17 = > 8 + g < 17 = > g < 9 = > at most 8 green balls answer : a"
subtract(8, const_1)