From the equation of motion, we know,

Where s= displacement
u= initial velocity
a= gravitational force
t= time
Displacement is 0 since the ball comes back to the same point from where it was thrown.
A =
since the ball is thrown upwards.
Plug the known values into the equation.
=> 
Solving for u gives :
u= 16.67 m/ sec ....... equation (1)
At maximum height, final velocity i.e v is 0
Time take to reach the top = 

=> 
Solving for s we get
s= 14.16 m
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The answer is 23 and 1÷9
First you multiply 4 by 5 and wind up with 20
Then you multiply four by 7÷9.
That gets you 28÷9
You take out all the nines you can from 28, three in this case.
That gets you 27÷9 + 1÷9
Your total thing is 20+27÷9+1÷9
That equals 20+3+1÷9
That equals 23 and 1÷9
Answer:
Adult=58
Step-by-step explanation:
c=child, a=adult
6.4c+9.7a=1145 equation 1
c+a=149 equation 2
a=149-c modified equation 2 to isolate a
6.4c+9.7(149-c)=1145 substitute value of a from equation 1 into equation 2
6.4c+1445.3-9.7c=1145
-3.3c=-300.3
c=91
solve for a
c+a=149
91+a=149
a=58
Check answer:
6.4c+9.7a=1145
6.4(91)+9.7(58)=1145
582.40+562.60=1145
1145=1145