If four fifth of the 30 students in the class were present, how many students were absent?

6 students were absent and this is because 1/5 (one fifth) = 6 students
1/5 x 4 (as there are four fifths) = 24 
30 - 24 = 6 

Hope that helped :)

24 present because 30/5 = 6  so 6x4 =24 so 24 students mate

Given number : travelling 45 miles /hours
Find the number of minutes will you spend if you travel 240 miles from Orlando to Miami
=> in 1 hour there are 60 minutes
=> 45 miles / hours is also equals to 45 miles / 60 minutes
=> how many 45 are their in 240
=> 240 / 45
=> 5.3, round to the nearest whole number = 5
=> 5 x 60
=> 300 minutes
=> 240 /300 minutes