Solve the following riddle:

I am a number,

Tell my identity!

Take me seven times over

And add a fifty!

To reach a triple century

You still need forty!

Let us assume the number be x

So, according to the riddle given in the question:

(7x + 50) + 40 = 300

7x + 90 = 300

7x = 300 – 90

7x = 210

Now,

We have to divide both the sides by 7

=

7x = 210

x = 30

Hence,

The required number be 30