Answer:
C
Step-by-step explanation:
By trial and error.
A: 50*12-100=500, 50*15-100=650. (A is not correct)
B: 500(12-11)=500, 500(15-11)=2000. (B is not correct)
C: 300(12-12)+500=500, 300(15-12)+500=1400. (if you continue try the numbers, you will see that this is the correct answer)
D: 200(12-5)+400=1800. (D is not correct)
