I think it is 32, bc the value of x is 20 so your problem would look like this; 2 ( (20) - 4 )
90 attempts are made and only one third are successful. Multiply the attempts by successes and you get 30 successful shots (90 x 1/3= 30).
3minutes 45 seconds = 3 45/60 = 3.75 minutes
28 copies/ 1 minute = x copies/3.75 minutes
using cross products
28 * 3.75 = 1 * x
105 = x
We can print 105 copies in 3 3/4 minutes
12.5 gallons..............
