Question

four times a certain 2 digit number is 7 times the number obtained on interchanging its digits. If the difference between the digit is 4; find the number​

Answer 1

Answer:

4[10x+y]=7[10y+x]

40x+4y=70y+7x

33x=66y

x=2y

x-y=4=2y-y

y=4

x=8

number=84