How many liters of water containing 7 grams of salt per liter must be combined with x liters of water which contains y grams [y is less than 2] of salt per liter to yield a solution with 2 grams of salt per liter.

Step-by-step explanation:

Let l litre of 7 grams of salt per litre is combined with x litres of water which contains y grams of salt per litre to yield a solution with 2 grams of salt per litre.

Thus,

Salt in l litre + salt in x litre = salt in resultant mixture

7l + xy = 2(l +x)

7l + xy = 2l + 2x

7l - 2l = 2x - xy

5l = x(2-y)

Hence, litres of 7 gram of salt per litre is mixed.

step-by-step explanation:

no, her answer is not correct.   we square the lengths of all sides and then determine whether the pythagorean theorem holds here:

9² + 15² = 306.   this is not equal to the square of the longest side ( that square being 395.   answer c is correct.

it is not that hard all u have to do is plot the graph

step-by-step explanation: