Explanation:
Let the number be x.
Now after adding 7 and 9 and taking the ratios of first and second the ratio becomes 4:5.
According to the given condition,
x+7 / x+9 = 4 / 5
5 (x+7) = 4 (x+9)
Cross multiplying both sides , we get
5x + 35 = 4x + 36
x = 1
The number obtained is 1.
The number that is added to 7 and 9 and when taken ratio gives 4:5