Answer: 67.5 minutes
Step-by-step explanation:
Since the front and backyard are the same size, then Alan will take the same time mowing them. So, if he takes 45 minutes mowing both of them, that means that he took half the time mowing the front and the other half mowing the backyard.
[tex]\frac{45}{2} =22.5[/tex]
The neighbor's front yard is the same size as well, so it will take him the same time.
[tex]45+22.5=67.5[/tex]
Then, the total time that Alan takes mowing the three yards is 67.5 minutes.