Set up a proportion, where x = the total number of students in 7th grade:
\(\frac{52}{x}=\frac{26}{100}\)
Then, cross multiply and solve for x:
\(\frac{52}{x}=\frac{26}{100}\\26x=5200\\26x/26=5200/26\\x=200\)
Therefore, there are 200 students in the 7th grade.