I don't understand the English. I would've loved to help though.
Amber spends $5,307.25 and she can make 461 skateboards.
Divide 1846 by 2 and you get 923, you then multiply that by $5.75 and get $5,307.25.
Then, you'll divide 1,845 by 4 and get 461.5. (she can only make 461 full skateboards.)
A billion has 9 zeros. So
15,000,000,000
:)
Given:
Violinists : Cellists = 7:3.
Number of violinists in the school orchestra = 21
To find:
The combined number of cellists and violinists.
Solution:
Let the number of violinists and cellists in the school orchestra are 7x and 3x respectively.
Then, combined number of cellists and violinists is

...(i)
Number of violinists in the school orchestra = 21

Divide both sides by 7.

Now, the combined number of cellists and violinists is
[Using (i)]

Therefore, the combined number of cellists and violinists is 30.