In 1 hour, he walked 1.8 miles.
We know, that he walked 1-1/4 miles in 5/12. First, we need to adjust the first term. 1-1/4 is 0.75 .. Now, we have to divide 0.75 by 5 .. That is 0.15 .. Now we now, that in 1/12 hour, he walked 0.15 miles. We want to know, how many kilometers did he walked in one hour. We just multiply 0.15 times 12. That is 1.8 miles.
I hope I helped you. I will be really happy, If you mark my answer as the brainliest.Your David