The answer is

.
Before we rationalize the denominator, we must simplify the numerator and denominator. We evaluate the square root on the top, and combine like terms on the bottom:

To rationalize the denominator, we multiply by the conjugate. The conjugate is found by making the imaginary term of the complex number, the i part, the opposite sign. The conjugate of -2-i is -2+i:
For this problem, we are going to use the <em>law of sines</em>, which states:

In this case, we have an angle and two sides, and we are trying to look for the third side. First, we have to find the angle which corresponds with the second side,
. Then, we can find the third side. Using the law of sines, we can find:

We can use this to solve for
:


Now, we can find
:

Using this, we can find
:


c is approximately 17.5.
Answer:
40% of the class is Girls, so 12 students are girls
Step-by-step explanation:
add up the ratio
2+3=5
divide by 5
30/5=6
multipy ratio to find totial number of students
2*6=12
2*3=18
divide the number of students to get the pecentage
12/30=0.4=40%
18/30=0.6=60%
1/4 off means 0.25 * 28
7
Sale price = 28-7
= 21