It means that you have to find the solution of the systems of equations.
Simplify the coefficient of z on the left side. We do this by rationalizing the denominators and multiplying them by their complex conjugates:








So, the equation is simplified to

Let's combine the fractions on the right side:


Then

reduces to

Multiply both sides by -1/(17 + 11i) :


Finally, simplify the right side:







So, the solution to the equation is

<h3>
Answer: A) 6</h3>
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Explanation:
Plug n = 6 and r = 5 into the nCr combination formula

Or you could use the shortcut

Yet another path you could take is to use Pascal's Triangle. Locate the row that starts with 1,6,... and then locate the second to last item. That value in the triangle is 6.
A real world interpretation is to consider having 6 people and you are selecting 5 of them to form a group where order doesn't matter. How many ways are there to do this? Well there are 6 such ways because there are 6 ways to leave someone out of the group.
The answer is 5/12 because 1/6 converts to 2/6 and 7/12-2/6 is equal to 5/12