Adam is going to cook a turkey for 14 people and wants to allow 3/4 lb of turkey for each person. 1lb = 450g

(You forgot to add the question, but I guess you want to know the mass of the turkey for 14 people :p )
By hypothesis, 1 lb = 450g. Adam wants that each of the 14 person, get 3/4 lb. Let x be the mass of 3/4 lb in grams, using the rule of three:

1 lb --> 450g
3/4 lb --> x

x = 3/4 * 450 = 337.5
So 3/4 lb = 337.5 g

Adam wants to cook for 14 people and wants to allow 3/4 lb of turkey for each person, so 337.5 for each.
So to know the total mass of the turkey, you multiply the mass for one person by the total  number of people:
337.5 * 14 = 4725
So the mass of the turkey for 14 people is 4725g, or 10.5 lb (3/4 * 14)

Hope this Helps! :)

3/4 = .75

.75 x 14 = 10.5 = 10 1/2

convert to grams = 10.5 * 450 = 4,725 grams

so he needs to cook a 10 1/2 lbs or  4,725 grams turkey for 14 people to allow 3/4 lbs each person.

Is there more to the question?