The original number is 38
A 2-digit number can be written as:
N = a*10 + b*1
Where a is the tens digit, and b is the units digit, these two are single-digit numbers.
We know that:
"the tens digit is 5 less than the units digit."
This means that:
a = b - 5
(notice that a must be larger than zero and smaller than 10, from this, we can conclude that b is a number in the range {6, 7, 8, 9})
"If you reverse the number, the result is 7 greater than double the original number"
The reverse number is:
b*10 + a
and this is 7 greater than 2 times the original number, then:
b*10 + a = 7 + 2*(a*10 + b)
Then we found two equations:
a = b - 5
b*10 + a = 7 + 2*(a*10 + b)
Replacing the first equation in the second, we get:
b*10 + (b - 5) = 7 + 2*((b - 5)*10 + b)
Now let's solve that:
b*10 + b - 5 = 7 + 2*(11*b - 50)
11*b - 5 = 7 + 22*b - 100
-5 - 7 + 100 = 22*b - 11*b
88 = 11*b
88/11 = b = 8
Now that we know that b = 8, we can use the equation:
a= b - 5
a = 8 -5 = 3
Then the original number is:
a*10 + b = 3*10 + 8 = 38
The original number is 38
If you want to read more about this, you can see:
https://brainly.com/question/19902993
