You know that of the 15 guests at your next party, 5 large eaters will eat 1 burgers each,...

You know that of the 15 guests at your next party, 5 large eaters will eat 1 burgers each, 5 children will eat  burger each, and the rest of the guests will each eat 1 burger. (a) How many burgers will you need, and (b) by what factor will you change the ingredient amounts?