A researcher needs 25 mL or 45% base Solution for a certain
expiriment, but she has only 15%
Solution and 65% Solution. How
many mL of the 15% and the
65% Solutions should she mix to
get what She needs?

10 mL of 15% solution

15 mL of 65% solution

Step-by-step explanation:

If x is the volume of 15% solution, and y is the volume of 65% solution, then:

x + y = 25

0.15 x + 0.65 y = 0.45 (25)

Solve with substitution:

0.15 x + 0.65 (25 − x) = 0.45 (25)

0.15 x + 16.25 − 0.65 x = 11.25

0.50 x = 5

x = 10

y = 15

6 adults and 9 children went.

a + c = 15

12a + 9c = 153

12(6) + 9(9) = 153

72 + 81 = 153