Answer:
B.56
Step-by-step explanation:
80x0.70 is 56
Answer:
The correct answer is D. The points are rotated 180 degrees and scaled by a factor of 0.5. I assume that the 0.5 is the expected value in the text box labelled "D" (for dilation perhaps?)
We know the yint, so lets find the slope. (0,-12) and (8,-2) -2--12/8-0 or 10/8 or 1.25
So, the slope is 1.25
The answer is y=1.25x-12
Let
be the 20 marks of the boys, and
be the 10 marks of the girls.
We know that the global mean was 70, meaning that

Multiplying both sides by 30 we deduce that the sum of the scores of the whole classroom is

By the same logic, we work with the marks of the boys alone: we know the average:

And we deduce the sum of the marks for the boys:

Which implies that the sum of the marks of the girls is 
And finally, the mean for the girls alone is

Answer:
x = 35.8°
Hope this helps...Have a good day!!