One-third of the sum of two numbers is 12, twice their difference is 12. Find the numbers.
- 22 and 14
- 20 and 16
-
21 and 15
- 23 and 13
The correct answer is: C
Explanation
Let the two numbers be x and y
\(\frac{1}{3}( x + y) = 12\)
then x + y = 36 ..........i
2( x - y) = 12
x - y = 6 ............ii
add equations i and ii
2x = 42
x = 21, put x = 21 into equation i
x + y = 36
21 + y = 36
y = 36 - 21 = 15
therefore the numbers are 21 and 15