I think this is right.. I tried my best. If u get it sorry... I’m very sorry
1. Divide 7.20 by 4 since the 4 are the pencils
2.divide 7.20 by 5 ( 5 represents the erasers )
3. Then finally multiply 1.44 from 7.20/5 and
2 and u get 2.88
Answer:
Using either method, we obtain: 
Step-by-step explanation:
a) By evaluating the integral:
![\frac{d}{dt} \int\limits^t_0 {\sqrt[8]{u^3} } \, du](https://tex.z-dn.net/?f=%5Cfrac%7Bd%7D%7Bdt%7D%20%5Cint%5Climits%5Et_0%20%7B%5Csqrt%5B8%5D%7Bu%5E3%7D%20%7D%20%5C%2C%20du)
The integral itself can be evaluated by writing the root and exponent of the variable u as: ![\sqrt[8]{u^3} =u^{\frac{3}{8}](https://tex.z-dn.net/?f=%5Csqrt%5B8%5D%7Bu%5E3%7D%20%3Du%5E%7B%5Cfrac%7B3%7D%7B8%7D)
Then, an antiderivative of this is: 
which evaluated between the limits of integration gives:

and now the derivative of this expression with respect to "t" is:

b) by differentiating the integral directly: We use Part 1 of the Fundamental Theorem of Calculus which states:
"If f is continuous on [a,b] then

is continuous on [a,b], differentiable on (a,b) and 
Since this this function
is continuous starting at zero, and differentiable on values larger than zero, then we can apply the theorem. That means:

First divide 29.79 feet by 6

But since you can't plant only a fraction of a tree, you can plant a maximum of 4 trees per row.
Now there are ten rows so...
10×4 = 40
You can plant 40 trees at the maximum.
2t+5v=37 and 4t+3v=39
Solve the first for t
t=18.5-2.5v and use this t in the second equation...
4(18.5-2.5v)+3v=39
74-10v+3v=39
-7v=-35
v=$5.00 and since t=18.5-2.5v
t=$6.00
So tuna sandwiches cost $6.00 and vegetarian sandwiches cost $5.00.