Question

the sum of digits of a a two digit number is 13 if if sum of their 12 is 89 find the number​

Answer 1

Answer:

Let ones digit =x. then tens digit = (17-x) Acordingly:-

Number=10×(17-x)+ x = 170 - 9 x……………..(1)

Again let each digit is z. after subtraction 12 from the number.

(170–9x)-12 =10z+z

158–9x=11z

z=(158–9x)/11………………….(2)

Now. we put x=1 , 2 , 3 ,………….9. and only on putting x= 9. then z=7. . this is the

only solution of eqn.(2)

Thus the number is from eqn.(1) by putting x=9.

Number= 170–9x. =170–9×9=170–81. = 89.