Answer:
The two features present in a plant cell, but not in an animal cell are chloroplasts and a large central vacuole.
Step-by-step explanation:
You should calculate( the area of a circle of radius 15 cm ) minus the area of the circle of radius (15 cm - width of the frame). I am not able to read the number, sorry.
That is the surface area of the frame.
Then, if area of circle radius is 100%, the % of face of the clock is:
(100xareaCircle(15cm-widthframe))/areaCircle15cm
Answer:

Step-by-step explanation:
-This is an LCM problem.
-To simplify, we introduce a least common multiplier which is equivalent the product of the denominators:

#We introduce the LCM and adjust the fractions based on it :

Hence, the simplified form of the fraction is: 
Answer:
the amount of time until 23 pounds of salt remain in the tank is 0.088 minutes.
Step-by-step explanation:
The variation of the concentration of salt can be expressed as:

being
C1: the concentration of salt in the inflow
Qi: the flow entering the tank
C2: the concentration leaving the tank (the same concentration that is in every part of the tank at that moment)
Qo: the flow going out of the tank.
With no salt in the inflow (C1=0), the equation can be reduced to

Rearranging the equation, it becomes

Integrating both sides

It is known that the concentration at t=0 is 30 pounds in 60 gallons, so C(0) is 0.5 pounds/gallon.

The final equation for the concentration of salt at any given time is

To answer how long it will be until there are 23 pounds of salt in the tank, we can use the last equation:
