Define a function

sumFstorSnds :: [(Integer, Integer)] -> Bool -> Integer

which adds up either every first component in a list of tuples if the second input is True or adds up every second component in a list of tuples if the second input is False

For example, sumFstorSnds [(1, 10), (2, 20)] True 3 and sumFstorSnds [(1, 10), (2, 20)] False = 30