Medication is prescribed in 6 out of every 10 hospital emergency room visits that involve an injury. if a large urban hospital had 930 emergency room visits involving an injury in the past month, how many of these visits would you expect included a prescription for medication?

We can first get the percentage of the emergency room visits that involves an injury. 
6 out of 10.
This will be (6/10)×100 = 60%

So, if there are 930 emergency room visits, the expected visits included a prescription for medication is;

60% of 930 = 60/100 × 930
                   = 0.6 ×930
                   = 558 

90 + (5x-2) + (2x+8) = 180
90 + 5x - 2 +2x + 8 = 180
7x + 96 = 180
7x = 180 - 96
7x = 84
x = 12

m<J = 5x - 2
m<J = 5(12) - 2
m<J =  60 - 2
m<J = 58