Question

9th question answer please

Answer 1

Step-by-step explanation:

9.

78 is the answer

if 9 is added to 78 it becomes 87

also the sum is 15 (7+8 =15)

Answer 2

Answer:

let x be the unit digit and y be the tens digit

x+y=15........... equation 1

and the original no. is x +10y

on reversing the original no.

10x+y

original no. = reversed no.

x+10y+9. = 10x+y

x-10x+10y-y+9=0

-9x+9y=-9

(taking -9as common)

we have

x-y=-9...…...... equation 2

by solving equation 1 and 2 by elimination method

subtract equation1 and 2

(x+y) - (x-y) =15-(-9)

2y=24

y=24/2

y=12

put y=12 in equation 1

x+y=15

x+12=15

x=15-12

x=3

and the original no. is =x+10y

=3+10×12

=3+36

=39

the unit digit is x=3 and the tens digit =y=12