Question

the sum of digits of two digit number is 9 if digits are reversed the new is decreased by 9 is equal to 4 times the original number find the original number​

Answer 1

Answer:

18

Step-by-step explanation:

Let ten's digit be x and unit's be y

∴ original no.=10x+y

∵x+y=9

⇒ x=9−y___(1)

New no. found by reversing the digits =10y+x

(10y+x−9)=4(10x+y)

⇒10y+x−9=40x+4y

⇒39x−6y=−9

⇒13x−2y+3=0

⇒13(9−y)−2y+3=0

⇒117+3−15y=0

⇒y=8

x=9−8=1

∴ The original no. is =10×1+8

=18