Answer:
n=0.4
Step-by-step explanation:
10:4=5:2
to make 5 as 1, we will divide both 5 and 2 by 5
<h3>

:

=1:n</h3><h3>therefore, n=

= 0.4</h3><h3 /><h3> </h3>
If the sum of two numbers is x
Then the equation is like this:
a+b = x
Then it says one of the number is 12. Change either a or b into 12
12 + b =x
If we want to find the other number, we need the make it into the subject
b = x - 12
Hope that help.