Question

Twice the sum of two numbers is 24. if one number is 2 times larger than the other, what is the smaller of the two numbers?

Answer 1

2(x+y)=24
2x=y

Use substitution. If y=2x, than we can substitute 2x for it in the other equation, because x and y equal the same things in both equations. 

So using that we get 2(x+2x)=24

SIMPLIFY
2(3x)=24

DISTRIBUTE
6x=24. 

DIVIDE: x=4.

If we substitute x into the original equations we get x=4 and y=8. Those are your two numbers. 

Have a nice day! :)