here's the solution,
rumba got 250 marks !!
if she had got 30 more marks then she would had passed the exam,
So, passing marks :
=》250 + 30
=》 280 marks
now, passing percentage :
=》
[tex] \dfrac{passing \: \: marks}{total \: \: marks} \times 100[/tex]
=》
[tex] \dfrac{280}{700} \times 100[/tex]
=》
[tex] \dfrac{280}{7} [/tex]
=》
[tex]40[/tex]
Hence, the passing percentage is 40%
