$$14^2 + 10^2 - \frac{11^2}{2\times{13}\times{10}}$$

$$196 + 100 -\frac{121}{260}$$

$$296 - \frac{121}{260} \approx 268.5346$$

Or if you meant:

$$14^2 + 10^2 -\frac{11^2\times{13}\times{10}}{2}$$

$$196 + 100 -({121\times{13}\times{5})$$

$$296 - 7865$$

$$-7569$$

$${\frac{{\mathtt{445.41}}}{{\mathtt{21.21}}}} = {\mathtt{21}}$$

Isn't the S.A. of a hemisphere:

pi*r^2 + (0.5)*4*pi*r^2 = S.A.

so . . .

3pi*r^2 = 618cm 

r^2 = 618/3pi

r = sqrt(618/3pi)

r approximately = 8.0976 cm 

2(x - 3) + 5x = 4(x + 2) -5 ..... Expand

2x - 6 + 5x = 4x + 8 -5 ...... Collect like terms

7x - 6 = 4x + 3 ....... Simplify

3x = 9

x = 3

To check:

2(3-3) + 5*3 = 4(3 + 2) - 5

0 + 15 = 4*5 -5

15 = 20 - 5

15 = 15

So the average of something is the sum of the various data points divided by the number of data points.

With two numbers it is also just the number in the middle of them eg. the average of 4 and 6 is 5.

$$\frac{61 + 81.5}{2}$$ = 71.25%

Hmm I have found a problem with this. Usually with grades different assessments have different weightings so without the total number of assessments and their respective % allocation of your total grade I don't believe this is possible. But the average of 61 and 81.5 is still 71.25.

If, for example, you had 4 assessments of equal weighting (25% each) you would collect them together as marks out of 25 and then add them to get a mark out of 100, or a percentage. 

lol ok this is why I don't like it when someone posts the same question twice. I just gave exactly the same answer this question's doppleganger 

$$\frac{34}{100} + \frac{5}{10}$$ = 

$$\frac{34}{100} + \frac{50}{100}$$ = 

$$\frac{84}{100}$$ =

$$\frac{21}{25}$$

Fingue out the following below:

Two ordered pairs: I'm assuming this means  (100, 14) and (200, 20) although I am not sure. 

Slope: Also called the gradient, or m, the slope is how much y increases in relation to x, in the form rise/run. In these two points; x increases by 100, and y increases by 6. So the slope is 6/100, or 3/50.

m = 3/50

Find b: b is the y intercept, which can be found when x = 0. If y goes down by 6 every time x decreases by 100 then the y-intercept has to be 8, according to the point (100, 14).

b = 8

Equation: y = mx + b is the slope-intercept form.

By substituting our values:

y = 3/50 x + 8

Lets check this for point (300, 26)

26 = 3/50 * 300 +8

26 = 900/50 + 8

18 = 900/50

18 = 18

yay :)

I think you may mean 25.5%, in which case:

25.5% = 25.5/100 = 51/200

Ooops didn't answer the question :)

It is 0.255. As a fraction it is: 25.5/100, so divide by 100. This is easily done by moving the decimal place over 2 to the left.