Answer: Length of side QR is 16 units.
Step-by-step explanation: Given that dimensions of PQR
QPR= 90degrees
5x+40 factors to 5(x+8). Notice how distributing the 5 back through to each term in the parenthesis gives
5 times x = 5x
5 times 8 = 40
So 5*(x+8) = 5*x+5*8 = 5x+40
Therefore, the factors are 5 and (x+8).
The dimensions of the sandbox are 5 feet by (x+8) feet.
We don't know the numeric value of (x+8) since we don't know the value of x, so we leave it as is.
Answer: There were 10 students in the class on the first day.
Step-by-step explanation:
Let x be the number of students of the first day.
Given: A college writing seminar increased its size by 50 percent from the first to the second day.
i.e. Number of students on second day = (Number of students on first day)+(50% of Number of students on first day)
= x +50% of x
= x+0.50x
= (1.50)x
=1.50x
Since, it is given that the total number of students in the seminar on the second day was 15.
i.e. 

Hence, there were 10 students in the class on the first day.
16 - 14 = 2
Think of it as in objects. You have 16 candies, and you eat 14. How many do you have left? You can count it and see. You have 2 left. So 16 - 14 = 2
Hope that helps :)