My friend is trying to rank up stop ok

The sum of two numbers is 12 and their difference is 18 what are the two numbers

An energy drink company claims that its product increases students' memory levels. to support its claims, the company issues advertisements claiming that 8 out of 10 people (chosen randomly from across the country) who tried their product reported improved memory. the missing component in this study is a .

Why is causation so much more difficult to prove than correlation?