i need help with Codingbat python

sum_teens

Given a list of integers, return the sum of teens (13-19, inclusive).

sum_teens([20, 28]) 0 sum_teens([29, 20, 19, 15, 6]) 34 sum_teens([18, 22, 10, 13, 17, 20]) 48

greatest_negative

Given a list of int values, return the greatest negative value. If there are no negative values, return zero.

greatest_negative([0, -9, -12, 6, 10, -15, 7]) -9 greatest_negative([-3, -2, 9]) -2 greatest_negative([-10, 8, -9, -15, 1, -4, 7, -1, 13]) -1

balance_point

The "balance point" is point where a list of values array can be split so that the sum of the numbers on one side is equal to the sum of the numbers on the other. (The balance point is included in the "second" sub-list.) Given a non-empty list of ints, return the balance point, or -1, in no balance point exists for the given list.

balance_point([1, 1, 1, 2, 1]) 3 balance_point([2, 1, 1, 2, 1]) -1 balance_point([10, 10]) 1