(10 PTS) How do I solve for this? Please show work

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 .

Solve for n? [tex]z = \frac{3}{4} mn[/tex]

What percent of 18 is 24? and plz explain thx.