How do you found any quantity of any ratio

Example : 10 : 3 if the first quantity is 300, then what is the second quantity

Answer: the second quantity is 90

Step-by-step explanation:

You divide the first quantity by the first ratio then multiply your answer by the second ratio

90

Step-by-step explanation:

Let C be the total of what they share.

Let A be the first

Let B be the second

A : B = 10 : 3

Total ratio = 10 + 3 = 13

From the question, were told that the first (i. e A) receives 300. Now we use this info to obtain the total of what they share as follows

A share is given by

(A ratio / total ratio) x total of what they share (C)

10/13 x C = 300

10C / 13 = 300

Cross multiply

10C = 13 x 300

10C = 3900

Divide both side by 10

C = 3900/10

C = 390

Now we can solve for B's share as

3/13 x 390 = 90

Therefore, the second obtained 90