Consider the problem of reasoning about the identity of a set from the size of its intersections with other sets. you are given a finite set u of size n, and a collection a1, . . , am of subsets of u. you are also given numbers c1, . . , cm. the question is:
1. does there exist a set x ⊂ u so that for each i = 1, 2, . . , m, the cardinality of x ∩ ai is equal to ci?
we will call this an instance of the intersection inference problem, with input u, {ai}, and {ci}.
2. prove that intersection inference is np-complete.

Choose the number sentence that shows the identity property of addition. a. 122 = 61 + 61 b. 62 = 1 + 61 c. 61 = 0 + 61

Ariana starts with 100 milligrams of a radioactive substance. the amount of the substance decreases by 20% each week for a number of weeks, w. the expression 100(1−0.2)w finds the amount of radioactive substance remaining after w weeks. which statement about this expression is true? a) it is the difference between the initial amount and the percent decrease. b) it is the difference between the initial amount and the decay factor after w weeks. c) it is the initial amount raised to the decay factor after w weeks. d) it is the product of the initial amount and the decay factor after w weeks.

How do i put 3(x+7) in distributive property