when average age of 20 members are 0 , how many members greater than 0 ?
"average of 20 numbers = 0 . sum of 20 numbers ( 0 x 20 ) = 0 . it is quite possible that 19 of these numbers may be positive and if their sum is a then 20 th number is ( - a ) answer is 19 ( b )"
subtract(20, const_1)