18. In a two-digit number, digit in unit's place is twice the digit in ten's place. If 27 is added to it, digits are reversed. Find the number.

the given number is (3×10)+6=36.

Step-by-step explanation:

Let x denote the digit in the tenth  place and y denote the digit in unit place..  So, the number may be written as x y 10 + in the expanded form. (just like 35= 10(3) +5)  

When the digits are reversed, x becomes the digit in unit place and y becomes the digit in the tenth place. The changed number, in the expanded form is 10y+x.

According to the first condition, we have y=2x which is written as  

2x−y=0      (1)

Also, by second condition, we have

(10+x)−(10x+y)=27

That is,   −9x+9y=27→−x+y=3            (2)

Adding equations (1) and (2),  we get  x= 3.  

Substituting x 3 = in the equation (2), we get y = 6.  

Thus,  the give

n number is (3×10)+6=36.

Hope this helps!

answer: howdy

step-by-step explanation: