First calculate the Subsets for set, then calculate the number of proper subsets {10,19,5,0}

The subsets of {10, 19, 5, 0} are

{ } - the empty set, or 1 subset of size 0

{10}, {19}, {5}, {0} - 4 subsets of size 1

{10, 19}, {10, 5}, {10, 0}, {19, 5}, {19, 0}, {5, 0} - 6 subsets of size 2

{10, 19, 5}, {10, 19, 0}, {10, 5, 0}, {19, 5, 0} - 4 subsets of size 3

{10, 19, 5, 0} - 1 subset of size 4

A proper subset of a set is any subset of that set that is not equal to that set. The only subset that is not a proper subset is {10, 19, 5, 0}, since that's the set itself. So there are 15 proper subsets.

In general, a set of size n has a total of 2ⁿ subsets, and 2ⁿ - 1 proper subsets.

50 min

step-by-step explanation:

they will be decreasing both their times in half

60 / 2 = 30

40/2 = 20

30 + 20 = 50