Answer:

Step-by-step explanation:
The question is not correct (particularly the expression for the area)
A=2lh+2wh
Now we are expected to solve for l, that is we are going to make l subject of the formula, we have
let us take the second term on the RHS to the LHS

we can now divide both sides by 2h we have

hence the expression for the length is 
Answer: X=40
Step-by-step explanation:
Answer:
112
Step-by-step explanation:
Define the variables:
x = number of French students sent by the school
Write the equation:
x / 21 = 1 / 3
Solve:
x = 7
The school sent 7 French students and 21 German students, for a total of 28 students.
The other 3 schools also sent 28 students. So the total number of students sent is:
4 × 28 = 112