The cost, c, for catering a luncheon using Right On Catering is c=120+12m+10v where m is the number of meat lunches and v the number of vegetarian lunches being served at the luncheon.

a.) Solve the equation for v.

b.) If the cost for the luncheon was $558 and 24 attendees ordered the meat lunches, how many vegetarian lunches were served?