This is the concept of algebra, to calculate the proportion of wool in each item we proceed as follows; Let the amount of wool used for hat be x amount of wool in sweater will be 5x the amount of wool used in scarf will be x-5 therefore the total amount of wool will be: x+5x+(x-5)=550 x+5x+x-5=550 7x-5=550 7x=550+5 7x=555 hence; x=555/7 x=79 the amount used in hat x=79g amount used in sweater 5x=395g amount used in scarf=79-5=74g