Question

The sum of a 2 digit number is 7. The 10's digit is 3 more than ones digit. What is the number?​

Answer 1

Answer:

 Let x = tems digit'

       y = ones digit

"sum of two digit number is 11"      means x + y = 11                 [eq1]

"tens digit is 3 more than the one digit"      means   x = y+3         [eq2]

Substitute (y+3) from [eq2] into [eq1]:

        (y+3) + y = 11

          2y + 3 = 11

             2y = 8

               y = 4

Now, use either [eq1] or [eq2] to find x.  Let's use [eq1]:

         x + y = 11    [eq1]

         x  + 4 = 11

             x = 7

The number is 74.

Check:

   Is   7 + 4 = 11   ?

             11 = 11   ? yes

   Is 7 = 4 + 3   ?

         7 = 7   ?yes

Step-by-step explanation: