A movie buff owns movies on DVD and on Blu-ray in a ratio of 7:2. If she buys 5 more Blu-ray movies, that ratio would change to 13:4. If she owns movies on no other medium, what was the original number of movies in her library before the extra purchase?  Choose the correct choice from the following answers
A) 22
B) 28
C) 77
D) 99
E) 351
if u can just keep an eye on the options   99 is the only multiple of 9 in options given .. SO you can mark it wid in seconds.   Now coming to the process m(D) = 7x and b(D) = 2x   now from the next line the new eqn becomes 7x/ (2x + 6) = 13/4   Solving it 28x = 26x + 78   x =39   which means m (d) = 273 and b(d) = 78   SO total initially is m(d) + b(d) = 351   351
<result>E</result>
A movie buff owns movies on DVD and on Blu-ray in a ratio of 7:2. If she buys 5 more Blu-ray movies, that ratio would change to 13:4. If she owns movies on no other medium, what was the original number of movies in her library before the extra purchase?