Question

The sum of the digits of a three digit number is 21. If the ten's digit
of the number is 5 more than units digit and units digit is half the
hundredth digit, what is the number?​

Answer 1

Answer : The number is 894

Explanation :

let the digits of three digit number are x, y , z .

As we have given,

the sum of the digits of a three digit number is 21

therefore , x + y + z = 21 ------(1)

the ten's digit of the number is 5 more than units digit

here, ten's digit is y and unit digit is z, therefore y = z + 5

And units digit is half the hundredth digit , so, z = 1/2 (x)

therefore, x = 2z

put the values of y and x in equation (1) ,we get,

x + y + z = 21

( 2z ) + ( z + 5 ) + z = 21

2z + z + z + 5 = 21

4z + 5 = 21

4z = 21 - 5

4z = 16

z = 4.

Now, y = z + 5 = 4 + 5 = 9

y = 9.

x = 2z = 2(4) = 8

x = 8.

therefore the number is 894.