A chemistry teacher needs to make 10 L of 36% sulphuric acid solution. The acid solutions available are 30% sulphuric acid and 50% sulphuric acid, by volume. How many litres of each solution must be mixed to make the 36% solution?

7 L and 3 L

Step-by-step explanation:

Given

Solution  has sulphuric acid by volume

Solution sulphuric acid by volume

final solution is of sulphuric acid

Suppose there is and of sulphuric acid of solution and respectively

So, quantity of acid before and after remains same

and total mixture before and after remains same i.e.

Solving  and   we get

So we get and

So, 7 liters from solution 1 and 3 liters from solution 2

walter needs to make at least 5 more cookies but no more than 40. 5 ≥ x ≥ 40;

step-by-step explanation:

walter has to make a minimum of 20 cookies. he already has 15 cookies made, so he must make 5 more to meet the minimum.

the maximum amount of cookies he can make is 55. he already has 15, so he has to make no more than 40 more cookies to meet the maximum.

$12. that is my answer.