Maria is preparing for exams in sociology and economics. She has time to read the 30 pages for sociology and 40 pages for economics in the same amount of time she could also read 30 pages of economics and 60 pages for sociology. Assuming that the number of pages per hour that she can read of either subject does not depend on how she allocates her time, determine how many pages of sociology could she read if she decided to spend all of her time on soc and none on econ?