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

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Answer:</h2>
The last answer - 9x squared y squared
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Answer:
its B :)
Step-by-step explanation:
I hope this helps ^^
To answer this, let the 3 sides of the regular sized rectangular box be x, y, and z.
When we double all the sides, the new sides have lengths 2x, 2y, and 2z, respectively.
Since the regular box (with dimensions x,y, and z) have 750 toothpicks, we can write

Similarly we can write for the jumbo box as,

which is equal to 
So this is 8 times the original of
. Hence the jumbo box will have 8 times 750 number of toothpicks.
ANSWER:
toothpicks