Answer:
Amount of 8% vinegar = 216 mL
Amount of 13% vinegar = 54 mL
Step-by-step explanation:
First, of all, let x be the amount of 8% vinegar used
Since, the scientist needs 270 mL of vinegar, then;
Let 270 - x be the amount of 13% vinegar used
Now, we are told that she needs 270 mL of a 9% vinegar.
This means that;
8%x + 13%(270 - x) = 9%(270)
Simplifying this gives;
0.08x + 0.13(270 - x) = 0.09 × 270
Expanding the bracket gives;
0.08x + 35.1 - 0.13x = 24.3
0.13x - 0.08x = 35.1 - 24.3
0.05x = 10.8
x = 10.8/0.05
x = 216 mL
Thus, she will need to use 216 mL of the 8% vinegar.
Since 270 - x is the amount of 13% vinegar used , then;
the amount of 13% vinegar = 270 - 216 = 54 mL
