What was the difference between number of Science graduate employees and Arts graduate employees in company C

Total number of employees in Company C increased by 40% from April, 2013 to April, 2014. If 50% of total number of employees in company C in April, 2014 were Commerce graduates, what was the number of commerce graduate employees in Company C in April, 2014

If the respective ratio between number of Arts graduate employees and Commerce graduate employees in company D was 4:9, What was the number of Arts graduate employees in Company D

Total number of employees in Company E was 3 times the total number of employees in Company B. If the difference between number of Commerce graduate employees in Company E and that in Company B was 300, what was the total number of employees in company B

The average number of Science graduate employees and Commerce graduate employees in Company A was 518. What is the total number of employees in Company A

The respective ratio between speed of the boat upstream and speed of the boat downstream is 3: 4. What is the speed of the boat in still water if it covers 70 km downstream in 3 hours 30 min ? (in km/h)