Answer:
67.3km/h
Step-by-step explanation:
Find the amount of time it took from 10:12 to 11:18.
Which is 66 minutes.
Find the average speed.
Formula of average speed =
Total distance/time
Which is,
74/66 = 1.121 (recurring decimal)
1.121 x 60 = 67.26km/h
= 67.3km/h (Estimated to 1 dp)
6.665 grams of the 13 grams remain after 8 hours.
<h3>How much of a 13 gram sample of iron-52 would remain after 8 hours?</h3>
The decay equation for the 13 grams of iron-52 is:

Where N is the amount of iron-52, and t is the time in years.
Where we used the fact that the half-life is exactly 8.3 hours.
Now, the amount that is left is given by N(8h), so we just need to replace the variable t by by 8 hours, so we get:

So 6.665 grams of the 13 grams remain after 8 hours.
If you want to learn more about half-life:
brainly.com/question/11152793
#SPJ1
Well.. instead of k he could have put 7. He should know that x and y are cut in half of their original values.
Hope I helped you!
ANSWER
The solution is

EXPLANATION
The given equations are:

and

We multiply equation 1 by 3 to get,

We multiply equation 2 also by 2 to get,

We subtract equation 4 from equation 3 to get,

This implies that,

We put this value of y into any of the equations say equation 2

Simplify

Group like terms

Simplify,

Divide both sides by 3 to get,

Therefore the solution is

The correct answer is option D.