27 Hours
Step-by-step explanation
Step 1
you can easily solve this by using a rule of three,
a) find the proportion
if
jack completed 68 math problems in 4 hours
Now, we have the proportion "the speed" of Jack.
Step 2
Let
x represents the time to finish 459 problems, the proportion is the same, so
Step 3
finally, solve for x
so, the answer is 27 hours