How do i do this math problem i have for homework?

Solve: 3x+y=6 4x-2y=18 show all work !

This is so hard and it’s for a test

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 .