Fifty students passed the math exam and 70 students passed the English exam. Five students failed these two subjects at the same time. In other words, 95 students have passed at least one subject.

Suppose two extreme cases, that is, everyone only passes one subject, then the total number of people is 50+70= 120, and the number of people who pass two subjects is zero at this time.

At the other extreme, I passed math and English at the same time, so 50 people passed two subjects and the rest 20 people passed English. Then the number of people who failed in both subjects is 100-70=30.

But in the first case, the total number of people does not meet the question. In the second case, the number of people who failed in both subjects does not meet the problem.

Therefore, let the number of people who pass both subjects be x,

The equation is: those who pass only math+those who pass only English+those who pass both subjects+those who fail both subjects = 100.

Then it is (50-x)+(70-x)+ x+5= 100.

x=25

The number of people who passed both subjects is 25.