Oi
Just calculating the differential. Step by step:

If you want to know where the tangent has no slope:
Answer:
A is the answer- Density = number of books over volume of shelf
Step-by-step explanation:
Density is mass/volume, so the number of books is the mass and the volume of the shelf is the volume for this equation.
Answer:
15. 6647.61
16. 553
Step-by-step explanation:
It is in the first quadrant
9. 1/3+(x+20)+(x-10)+40=360 10. 1/2x+1/2x+(x-15)+(x-25)+100=540
1/3+2x+50=360 4x+60=540
(3/1) 1/3+2x=300(3/1) 4x/4=480/4
2x=300 X=120
————
2
W=150