Question 825009
Let x = the smaller number, and y = the larger number.

Here is the problem written as a pair of equations:

{{{x+y = 51}}}
{{{y-2x = 18}}}

One method that can be used to solve this is the system of elimination. Subtract the second equation from the first one to isolate the x variable.

{{{3x = 33}}}
Simplify: {{{x = 11}}}

Now, plug the number into one of the two equations.

{{{11+y = 51}}}
Subtract 11 from both sides to isolate the y variable: {{{y = 40}}}

You can check your answer by plugging the numbers into the other equation. {{{40-22 = 18}}}

The smaller number is 11, and the larger number is 40.