The sum of two numbers is 40....

​The sum of two numbers is 40. The larger number is 20 more than the smaller number. What are the two numbers?

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x = smaller number
x + 20 = larger number

x + x + 20 = 40   {sum of two numbers is 40}
2x + 20 = 40  {combined like terms}
2x = 20  {subtracted 20 from each side}
x = 10  {divided each side by 2}
x + 20 = 30   {substituted 10 back into x + 20}

10 and 30 are the two numbers

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