Question

a number consists of two digit and the sum of the digit is 12 . the digit at ones place is three times the digit at tens place .
find the number

Answer 1

Let the two digits be

X and Y

Therefore the no is x+10y       (as y is at tens place)

A.T.Q

x+y=12-----------------------(1)

x=3y--------------------------(2)

From 1

x=12-y

putting the value of x in eq 2 we get

12-y=3y

12=3y+y

12=4y

y=3-------------------(A)

x=3y----------------------(from 2)

x=3(3)

x=9---------------------------(B)

From A and B

the no is

x+10y

⇒9+10(3)

⇒9+30

⇒39 is the no.