In approximately 10 years the oak tree population will be 50% of what it is. because 5 x 10 = 50. hope this helps :)
Subtract the two Y values of X = 2 and X = 4 to find the total difference, then divide by the difference between X=2 and X =4
When X = 2 Y = 9
When X = 4 Y = 64
Difference between the two Y values = 64 -9 = 55
Difference between the two X values = 4-2 = 2
The rate of change = difference in Y divided by difference in X:
55/2 = 27.5
If you're solving for x:
-4x + 6 = 26
- 6 - 6
-4x = 20
/-4 /-4
x = -5