Answer:
15.

16. 10 ml of 20% saline and 40 ml of 10% saline
Step-by-step explanation:
A chemist takes x ml of 20% saline and y ml of 10% saline. In total, he takes
x + y ml that is 50 ml, so

There are
ml of salt in x ml of 20% saline and
ml of salt in 10% saline. There are
ml of salt in 50 ml of 12% saline. Thus,

15. We get the system of two equations:

16. Solve this system. From the first equation:

Substitute it into the second equation:

This is easier than you think!
When a graph shows direct variation, it always <em>passes through the origin</em>
The origin is (0, 0)
The very <u>center! </u>
Your answer is the first graph!
Answer:
I don't think so
Step-by-step explanation:
Answer: D
Step-by-step explanation: