The diagram below shows the arrangement of seats in the first three rows of an auditorium.

if this pattern continues throughout the auditorium, how many seats will be in the 21st row?

a.84

b.82

c.86

d.90

the rows are under the answers for this question in order to answer it.

Can someone answer this question? : )

Find the volume of the described solid.the solid lies between planes perpendicular to the x-axis at x = 0 and x=7. the cross sectionsperpendicular to the x-axis between these planes are squares whose bases run from the parabolay=-31x to the parabola y = 30/x.a) 441b) 147c) 864d) 882

Ineed with number 6 , explain how to get 1978