# sum_of_values
my_dict = {"a": 5, "b" : 3, "c" : 10}
list_of_strings = ["a"]
def sum_of_values(my_dict, list_of_strings):
    for val in sum_of_values:
        for key, value in my_dict.items():
            if my_dict.keys() == list_of_strings:    
    return sum(value)
sum_of_values(my_dict, list_of_strings)