The sum of two numbers is 15. If one number is subtracted from the other, their difference is 3. Find the numbers.

Question

i need help with this problem can you help me?

Answer 1

Let one number be x and the other y.    So     x + y = 15

                                                         and    x -  y =   3                                                                                                                                                                    __________

   adding these together makes                    2x       =  18

dividing both sides by 2  we get                     x       =   9

finally x + y = 15  or 9 + y = 15   so             y        =   6

 

You should be able to plug the numbers back in to both equations and have it work.

9 and 6 do add up to 15 and their difference is 3.

Answer 2

Let n be the larger of the two numbers. The other number is 15 - n, so 

 

n - (15 - n) = 3

 

n - 15 + n = 3

 

2n - 15 = 3

 

2n = 18

 

n = 9

 

So the larger number is 9 and the smaller number is 15 - 9 = 6.