Karen can read 10 pages and complete 15 mouth problems in 30 minutes. How long will it take her to do homework if she has 30 pages to read and 45 math problems to complete your answer should refer to the amount of time in minutes.
If Karen can read 10 pages and complete 15 math problems in 30 minutes, then in 30 minutes she can read 30/10 = <<30/10=3>>3 sets of 10 pages.
In 30 minutes, Karen can complete 3 sets of 15 math problems, which is a total of 3*15 = <<3*15=45>>45 math problems.
To complete 30 pages and 45 math problems, it will take Karen 30/10 + 45/15 x 30 = 3 + 45/15 x 30 = 3 + 3*45 = 3 + 135 minutes. Answer: \boxed{138}.