If you are going 80 mph how long does it take to go 40 miles

               (40 mile) / (80 mile/hour)

           =  (40 / 80) (mile-hour/mile)  =  1/2 hour .

First you get p on the side by itself p=1/10-1/5+1/2. Next you find a common denomenator which is 10 so p=1/10-2/10+5/10 and you get 4/10 which reduces to 2/5. To check this on a Ti-84 calculator store 2/5 for x and put x in the place of p and type in the equation and your answer will be 1/10