20% of the seventh-grade students have math class in the morning. 16 2/3 % of those students also have science class in the morning. if 30 seventh-grade students have math class in the morning but not science class, find how many seventh-grade students there are.

Let x be the number of seventh grade students.

The 20% of the seventh grade students have math class in the morning means mathematically is 20/100.

The 16 2/23% of those students also have science class in the morning means:

16 2/3 & 20/100 = also have class in the morning
83 1/3 * 20/100 = math in the morning but not in science in the morning

30 students have math in the morning but not science in the morning

83 1/3% * 20/100% * x = 30
250/3 * 20/100x = 30
x = 180

There are 180 seventh graders.