31. a) The sum of the digits of the two
digit number is 12. The number obtained
by interchanging the two digits exceeds
the given number by 18. Find the
number. (OR) b) A motor boat covers a
distance of 16km upstream and 24km
downstream in 6 hrs. in the same time it
covers a distance of 12km upstream and
36km downstream. find the speed of
the boat in still water and that of the
stream.
Answers
Answer:
Step-by-step explanation:Let the tens digit of the required number be x and the units digit be y. Then,
x+y=12 .........(1)
Required Number = (10x+y).
Number obtained on reversing the digits = (10y+x).
Therefore,
(10y+x)−(10x+y)=18
9y−9x=18
y−x=2 ..........(2)
On adding (1) and (2), we get,
2y=14⟹y=7
Therefore,
x=5
Hence, the required number is 57.
Answer:
pls mark it as the brainliest
Step-by-step explanation:
Let the tens digit of the required number be x and the units digit be y. Then,
x+y=12 .........(1)
Required Number = (10x+y).
Number obtained on reversing the digits = (10y+x).
Therefore,
(10y+x)−(10x+y)=18
9y−9x=18
y−x=2 ..........(2)
On adding (1) and (2), we get,
2y=14⟹y=7
Therefore,
x=5
Hence, the required number is 57