The equation (form) is: 
The solution of the equation is: 
Explanation:
First, let's call the number we are going to solve for "x".
Then two thirds of this number can be written as:

Then "plus 4" means add 4 we get:

"is 7" means that the above expression is equal to 7 (as follows):

The solution of the above equation is:

Answer:
y=12x-16
Step-by-step explanation:
y-y1=m(x-x1)
y-20=12(x-3)
y=12x-36+20
y=12x-16
Step-by-step explanation:
This is an exponential increase. As represented in the picture, approximately 77 lilly pads will be produced after 50 days when there is initial of 22.