Question 1197100
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Method 1


8 problems = 20 min
8/20 problems = 20/20 min
0.4 problems = 1 min
The unit rate is 0.4 problems per minute


x = number of minutes
(unit rate)*(number of minutes) = amount done
0.4x = 30
x = 30/0.4
x = <font color=red>75</font>
You'll need <font color=red>75 minutes</font> to do 30 problems assuming you can keep the same rate going.


Side note:
75 min = 60 min + 15 min = 1 hour + 15 min
or
75 min = 1 hour + 15 min = 1 hour + (15/60) hour = 1 hour + 0.25 hour = 1.25 hours



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Method 2


(8 problems)/(20 min) = (30 problems)/(x minutes)
8/20 = 30/x
8x = 20*30
8x = 600
x = 600/8
x = <font color=red>75</font>


Answer:  <font color=red>75 minutes</font>
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