Question

Q6. Seven times a 2- digit number is equal to four times the number obtained by reversing the order of the digits . If the sum of both the digits is 9 , find the number.

This is linear equation in 2 variables and this is a grade 10 problem.

Answer 1

Answer:36

Step-by-step explanation7(10x+y)=4(10y+x)

70x+7y=40y+4x

66x-33y=0

2x-y=0 , 2x=y.....1

Also,

x+y=9....2

From 1 and 2

x+2x=9

3x=9

x=3

So, y=2(3)=6

Answer 2

Answer:

Answer:

The required number is 36.

Step-by-step explanation:

SOLUTION:

Let numbers be x at ones place & y at tens place so,

10y+x is the digit.

Reversed digit =10x+y

According to the question,

∴7(10y+x)=4(10x+y)

⇒x=2y⟶(i)

Now,

Given, x+y=9

from equation (i)2y=x substitute in the above equation.

2y+y=9

y=3

So,

x=2y=2×3=6

∴ Required original no: is =10y+x=10×3+6=36.

We can also check that the sum of the digit of 36 is 9. (3+6=9)