Correct answer is E. You can also use the easy
Plug-In method: You want to find out c:m:e and have the terms
I) (3000c+6000m/(c+m)) = 4000
II) (3000c + 10000e/(c+e)) = 5000
Now, start with
C. 10:4:3
Plug in 10 and 4 for c and m, respectively, into the first term I).
3000*10 + 6000*4 / (10 + 4) = 54,000 / 14.
You should see, that this does not equal 4000. Cross out C.
However, the answer was quite close (4000*14 = 56,000), so
let´s move on with D, since there are similar numbers.
3000*10 + 6000*5 / (10 + 5) = 60,000 / 15 = 4000
Nice! This one fits. Now, we only have to try out whether the answer also fits into the second term II):
3000 * 10 + 10000*2 / (10 + 2) = 50,000 / 12 =/= 5000
--> Cross out D.
Now, since E is similar to D (c:m is the same),
let´s try out E:
3000 * 10 + 10000 * 4 / (10 + 4) = 70,000 / 14 = 5,000
This is it! You have found the right answer: E.