Question

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.

Answer 1

Let the number be $n$.
According to the question, $7n+50+40=300$
$\Rightarrow 7n+90=300\Rightarrow 7n=300-90$
$\Rightarrow 7n=210$
$\Rightarrow n=\frac{210}{7}$
$\therefore n=30$
Thus, the required number is $30$.