This question can absolutely be solved by TESTing VALUES. Here's how:
You can see from the answer choices that there are 5 variables, so you want to keep your values relatively simple. Before I TEST any values though, I'm going to take some quick notes on what the prompt tells us:
X% commission on M players @ $P/player
Y% commission on (M+Q) players @$P/player
We're told that Y > X and it's implied that all values are > 0.
Here are my VALUES:
X = 10 (percent)
Y = 50 (percent)
M = 1 (player)
Q = 2 (players
P = 10 (dollars)
Using these values, we get...
10% of 1 player @$10/each = 10%($10) = $1
50% of 3 players @$10/each = 50%($30) = $15
The DIFFERENCE = $14
Since the answer choices are suitably "crazy"-looking, we need to take advantage of any repeating patterns (such as P/100 = 10/100 = 1/10) and math "shortcuts" so we can avoid any unnecessary work.
Answer A: (1/10)[50 - 30] = $2 Not a match
Answer B: (1/10)[30 + 50] = $8 Not a match
Answer C: 10[-50 - 10] = NEGATIVE. Not a match
Answer D: (1/10)[30 - 50] = NEGATIVE. Not a match
Answer E: (1/10)[150 - 10] = $14 MATCH
GMAT assassins aren't born, they're made,