Firstly we have rewrite the word problem into Mathematical form:

Let's assume :

x = the 10's digits

y = units

Then the original number:

10x + y = two digit number

Now lets write down what's given in the problem:

x + y = 10

Re-written as: y= 10 -x (equation 1)

We are also told the number obtained by interchanging the two digits exceeds the number by 36:

interchanged = original + 36

10y + x = 10x + y + 36

9y = 9x + 36

y = x + 4

Now equate the above equation to equation 1

10 - x = x +4

2x = 6

x = 3

Now find y:

x+ y =10

y= 10 - 3

y = 7

Now we are required to find the original number. From above the equation of the original number is:

10x + y = 10(3) + 7 =37

**The original number is 37**