Question

The sum of two numbers is 52. If twice the smaller number is subtracted from the larger number, the result is 13. Find the two numbers.

Answer 1

To solve this equation, you know you have two numbers which you can represent with x and y. 
Larger number = y         Twice the smaller number subtracted from the larger
Smaller number = x       is equal to 13:

y - 2x = 13      Solve for y:    y = 2x + 13      Then substitute your value for y into the equation they gave you at the beginning:

(2x + 13) + x = 52    Solve the equation by simplifying:
3x = 52 - 13       3x = 39    x = 13           Then substitute your value for x (13) into the equation we made to solve for y:
y - 2(13) = 13      y - 26 = 13     y = 39     
So your answer is, "The two numbers are 13 and 39."