Okay let's solve both:
#11:
If we input the values 2 and 4 into a - 3b, we get:
2 - 12 = -10
The answer is option E
#12
Knowing that 125 is 1/4 of a plane ticket and that you need 5, you would have to multiply by 4 (To cancel the 1/4) and multiply by 5.(Because you need five tickets)
Because 4*5 = 20,
The answer is option E