Question

find the number such that one of them exceeds The Other by 9 and their sum is 81

Answer 1

Solution :

Let one number = x ,

second number = x + 9

According to the problem given ,

x + x + 9 = 81

=> 2x + 9 = 81

=> 2x = 81 - 9

=> 2x = 72

=> x = 72/2

=> x = 36

Therefore ,

one number = x = 36

second Number = x + 9

= 36 + 9

= 45

•••••

Answer 2

Sol:

     Let the first number = X (variable) Then the second number = X +9

X+(X+9) = 81

2X+9= 81

Send 9 to RHS

2X=81-9 (the sign of the number changes. + INTO - AND - INTO +)

2X=72

Send 2 to RHS

X=72/2 (× into ÷ and ÷ into ×)

After cancellation

X= 36

First number = X

                     = 36

Then, Second number = X+9

                                      =36+9

                                     =45

 

Therefore the first number is 36 and second number is 45