All students in the 6th grade either
have a libary card or don't.
20% don't have a libary card
160 do have a libary card

40 students without a library card.

200 students overall

Step-by-step explanation:

First of all, the 160 students with a library card are 80% of the students.

So we're trying to find 20% or how many have one over all? I'll answer both then.

First, you might want to set up a table or double number line if that helps. You should have 80%=160 filled in if you're doing that.

To find 20%, you should do 160 divided by 4. This is because %80 divided by 4 is %20, and 160 also needs to be divided by 4.

160 divided by 4 is 40. So 40 students don't have a library card.

To find out how many students there are overall, just do 40 plus 160 equals 200.

constant acceleration- a

constant velocity- c

no velocity or acceleration- b

explanation:

for body moving with a constant acceleration, the rate of change of displacement changes over time. this is proven by the increasing gradient of the curve (a) against time.

a body that is moving at constant velocity covers equal distances over equal periods of time, thus the straight line with a constant gradient c.

a stationary body   covers no displacement as time elapses. thus the flat line with   zero gradient.