We consider buying three kinds of food. food i has 1 unit of vitamin a, 3 units of vitamin b, and 4 units of vitamin c. food ii has 2, 3, and 5 units, respectively and food iii has 3, 0 and 3 units, respectively. we need to have 11 units of vitamins a, 9 of vitamin b, and 20 of vitamin c. (a) find all possible amounts of three foods that will provide precisely these amounts of vitamins. (b) if food i costs 60 cents and the others cost 10 cents each per unit, is there a solution costing exactly 100 cents.

Ariana starts with 100 milligrams of a radioactive substance. the amount of the substance decreases by 20% each week for a number of weeks, w. the expression 100(1−0.2)w finds the amount of radioactive substance remaining after w weeks. which statement about this expression is true? a) it is the difference between the initial amount and the percent decrease. b) it is the difference between the initial amount and the decay factor after w weeks. c) it is the initial amount raised to the decay factor after w weeks. d) it is the product of the initial amount and the decay factor after w weeks.