Question

There is a two digit number whose 2nd digit is 4 less than the first digit. and the number itself is 7 times the sum of its digits. what is the number

Answer 1

Gargi ji ,first of all always remember no formation (10x+y),here x is first no. And y is second no. Ok now according to ur question y=x-4 ,& 7(x+y)=10x+y solve these equations we get x=8 and y=4 so no is 84.ok if u no able to solve equations then again msg me.ok keep working and nice nyt

Answer 2

Answer:

84 is the required two digit number .

Step-by-step explanation:

Explanation :

Given two digit number whose 2nd digit is 4 less than the first digit

and the number itself 7 times the sum of its digits .

Let the first digit be x and second digit be y

So , the two digit number is (10x + y )

Step 1:

Now according to the question , second number is 4 less than the first digit .

⇒ y  = x - 4  ......(i)

And the number itself is 7 time the sum of its digits

⇒ (10x + y ) = 7 (x + y)

⇒10x - 7x + y - 7y = 0

⇒3x - 6y = 0

⇒ x - 2y = 0  ......(ii)

Step 2:

Now , put the value of y from equation (i) in equation (ii)

⇒  x - 2(x - 4 )= 0

⇒ x - 2x + 8 = 0

⇒-x = -8 ⇒ x = 8

Now put the value of x = 8 in any one of the equations we get ,

x - 2y = 0

⇒8 - 2y = 0

⇒ -2y = - 8 ⇒  y = 4

xy  is  84

Final answer :

Hence , the  two digit number is 84 .

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