At a certain high school, the senior class is twice the size of the junior class. If 3/8 of the seniors and 1/4 of the juniors study Japanese, what fraction of the students in both classes study Japanese?  Choose the correct choice from the following answers.
A) 1 / 2 B) 2 / 3 C) 1 / 4 D) 1 / 3 E) 3 / 4

Rationale: "start by deciding on a number of students to represent the number of students in the senior class . for this example i will choose 200 students . that would make the number of students in the junior class 100 . then we can find out how many students are taking japanese in each grade and add them together . ( 3 / 8 ) * 200 = 75 and ( 1 / 4 ) * 100 = 25 . 75 + 25 = 100 . there are a total of 300 students in the junior class and senior class combined ( 100 + 200 = 300 ) , and there are 100 total students in japanese , so 100 students in japanese / 300 total students equals 1 / 3 of the students in both classes that study japanese . answer : d"
Answer: D