70,000 when a zero is in between you gonna count it
((7 + 5)^2) / (4 * 3 + 9) =
(12^2) / (12 + 9) =
144 / 21 reduces to 48/7 or 6 6/7
<h3>Option C</h3><h3>The average rate of the reaction over the entire course of the reaction is:

</h3>
<em><u>Solution:</u></em>
Average rate is the ratio of concentration change to the time taken for the change

The concentration of the reactants changes 1.8 M to 0.6 M
here, the time interval given is 0 to 580 sec
Therefore,

Thus option C is correct
Answering from phone so this will be a bit messy.
a
b=a+1
c=b+1=a+2
2a=b+20
Therefore:
2a=a+1+20
a=21,b=22,c=23