Question

4. A certain number between 10 and 100 is 8 times the sum of its digits, and if 45 be subtracted from it the
digits will be reversed. Find the number.​

Answer 1

Answer: 72

Step-by-step explanation:

let the ten's digit be x and one's digit be y,

the number = 10x+y

now , 8(x+y)=10x+y

8x+8y=10x+y

7y=2x

y=2/7 (x)

now,

10x+y-45=10y+x

9x-45=9y

9(x-y)=45

x-y=5

put y=2/7(x) in x-y=5

x-2/7(x)=5

7x-2x/7=5

5x=35

x=7 ,

put x=7 in x-y=5

7-y=5

y=2

therefore our number is , 10x+y

10(7)+2=72