Derek would have planted the tree 7 years ago. You subtract 36 from 44.75 and get 8.75. This is how much the tree grew since he planted it. Then, you'll divide 8.75 by 1.25 (1 1/4) which tells you how many years it has been since he planted the tree. The final answer is 7 years. Hope this helps!
The series of numbers is adding 5 and then subtracting 2
20+5=25
25-2=23
23+5=28
28-2=26
and so on. Do you understand?
24 students / 3 groups = 8
8 parents will be needed to put the students into groups of 3.
For this case we have the following function:

To find the distance between the pillars, we must match the equation to zero:

From here, we clear the value of d:

The roots are:
Root 1:

Root 2:
Thus, the pillars are 40 units away.
The maximum height, we obtain it by deriving:

We equal zero and clear d:

Then, we substitute the value of d = 20 in the equation for the height:
The maximum height is 10 units of distance
C.the diagonals are perpendicular i think :D