To disinfect one quart of stream water to make it drinkable you need to add two tablets of iodine. How many tablets do you need to disinfect 4 quarts

It is already given in the question that 2 iodine tablets are required to disinfect 1 quart of stream water. The thing that needs to be found is the number of tablets required to disinfect 4 quarts. As can be seen in the question, the information's provided are enough to get to the desired answer.

Then

Number of tablets required to disinfect 1 quart of stream water = 2

Number of tablets required to disinfect 4 quart of stream water = 2 * 4

= 8

So 8 iodine tablets are required to make 4 quart of stream water drinkable.