Find each sum or difference. write in simplest fraction form.

7/8 - 1/4 =

5/6 + 1/2 =

3/5 - 2/7 =

and also can someone me with this! ?

pamela ran 7/10 mile on tuesday and 3/8 mile on thursday. how much farther did she run on tuesday?

1. 2 miles
2. 13/40 miles
3. 3/40 miles
4. 5/9 miles

Monitors manufactured by tsi electronics have life spans that have a normal distribution with a standard deviation of 1800 hours and a mean life span of 20,000 hours. if a monitor is selected at random, find the probability that the life span of the monitor will be more than 17,659 hours. round your answer to four decimal places.

During the election for class president, 40% of the students voted for kellen, and 60% of the students voted for robbie. 500 students voted in total. how many more students voted for robbie than for kellen? answer with work : )

Officer brimberry wrote 32 tickets for traffic violations last week, but only 4 tickets this week. what is the percent decrease? give your answer to the nearest tenth of a percent.