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:
Step-by-step explanation:
hope this helps have a great day!
Answer:
<em>( - 15, - 16 ) </em>
Step-by-step explanation:
Coordinates of midpoint are ( 
, 
)
( - 5 + x ) / 2 = - 10 ⇒ x = - 15
( 4 + y ) / 2 = - 6 ⇒ y = - 16
<em>( - 15, - 16 )</em>
