Hi and welcome to the board.
First of all: do not post a screenshot but a question as text.
Here are the rules for posting on the board
rules-for-posting-please-read-this-before-posting-1083.html and the way how to post a question in the right manner
qq-how-to-post-a-gre-question-the-easy-way-2357.html.
Post also under the right section. Ask GRE expert is the section for asking: how long is the test, how many sections it has ...and so on...
Back to the question. For me is not a good question. which is the source?
if the machine produces \(a\) bolts in 15 minutes, we can assume if a = 5 the machine produce ONE bolt in 3 minutes. Now, if it produces 5 bolts in 15 minutes we do know that for instance in c hours, 1 hour, the machine does 20 bolts.
But quantity B says 3ac. considering c = 1 and a = 5 then 3*5 = 15 that is not possible.
However, yes B is always greater than A.
Ask if something is still unclear to you.
Regards