A man has 350 watches.He sells w watches everyday.Write an algebraic expression to show the number of watches he would be left with after t weeks.

watches sold in 1 day=w
watches sold in 7 days (1 week) = 7 * w

watches sold in t weeks = 7 * w * t
total watches =350

suppose watches left =z

so
350 - (7 * w * t) = z