Find the rate in which both balls make one full rotation around the track.
Ball A:

It takes 30 seconds for Ball A to make a full rotation.
Ball B:

It takes 20 seconds for Ball B to make a full rotation.
Find the least common multiple of 20 and 30 to find the time at which they'll meet.
Multiples of 20: {20,40,60}
Multiples of 30: {30,60}
60 is the least common multiple of both 20 and 30.
The balls will meet again at
60 seconds.
$230 divided by 1/4 = 57.5
Answer:
7z^3+6z^2-27z+22
Step-by-step explanation:
The given question is of subtraction:
So,
(7z^3+42z^2-15z+1)- (36z^2+12z-21)
=7z^3+42z^2-15z+1-36z^2-12z+21
Combining alike terms to simplify
=7z^3+42z^2-36z^2-15z-12z+1+21
=7z^3+6z^2-27z+22
So the answer in simplified form is:
7z^3+6z^2-27z+22 ..
1). 2x-1>0
2x>1
x>½
2) 21-3y<0
-3y<-21
y>7
3) 5-3c>80
-3c>75
c<-25