Here the answer is 19/35
Step-by-step explanation:

We will apply BODMAS rule
In this rule multiplication comes before add and subtraction
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Answer:
20.
Given, complex number is 10+5i .
We need to find sum of the given complex number and its conjugate. The conjugate of 10+5i is 10-5i. Therefore, the sum will be 10+5i+10−5i=20.
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:
