John got 20% marks in an examination and failed by 10 marks. In the same examination, Jack got 35% marks which were 20 more than the minimum passing marks. Find the percentage of minimum marks required to pass.

Percentage of marks = $$\frac{\text {Marks obtained}}{ \text { Total Marks }} \times 100$$ 

Let the total marks = x ,

According to the question; 

​$$\frac{20}{100}\times x +10 = \frac{35}{100} \times x -20$$ 

0.35x - 0.20x = 30 

0.15x = 30 

x = 200 

Now, passing marks = $$\frac{20}{100} \times 200 + 10 = 50$$  

Required % = $$\frac{50}{200} \times 100 = 25\%$$​​

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