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:
10+2x
the tree would be 40 feet tall in 15 years.
Answer:
17.5
Step-by-step explanation:
Given that:
20% apple juice drink is mixed with a 100% apple juice drink.

represents the concentration of apple juice in the drink when
gallons of 20% drink are added to 2 gallons of pure juice.
Also, given that 6 gallons of 20% drink are added to the 2 gallons of pure juice.
To find:
The concentration of apple juice in the drink = ?
Solution:
Given the function:

and


In percentage, the concentration 17.5.
Answer:
2×10−4
Step-by-step explanation:
To change 0.0002 to scientific notation, move the decimal to the right 4 places so that you get 2. The exponent on the base 10 will be -4 because the decimal was moved to the right 4 places