Question

a two digit number is such that the product of the digit is 20 if 9 is subtracted from the number then the digits are reversed find the number​

Answer 1

Answer:

54

Step-by-step explanation:

Let the digit at ten's place be x and the digit at one's place be y.

then no. will be 10x+y

GIVEN- xy=20...................(1)

also, 10x+y-9=10y+x

or, 10x-x+y-10y=9

9x-9y=9

9(x-y)=9

x-y=1...................(2)

x=1+y

IN EQ.(1) ,(1+y)y=20

y+y²=20

y² +y-20 =0

y²+5y-4y-20=0

y(y+5)-4(y+5)=20

(y+5)(y-4)=0

therefore,y=-5. or. y=4

y=-5 is not possible as y is a digit and digits are always positive.

THEREFORE,y=4 and x=1+y from EQ.(2)

x=5

no.=10x+y=. 10*5+4

no.=54