Jim drove the 120 miles to grandmother's house in 3 hours. he increased his speed by10 miles per hour on the way home. how long did it take him to drive home?

Ok so basically you want for this specific problem to set up a proportion.  So 120 mi/3hours=x/10 miles. X is the unknown variable we are solving for so pay close attention. So now I am going to multiply 120 times 10 which is 1200 now that divided by 3 is 400. Hoped this helped !!!

Well if he drove there in 3 hour and went 120 miles then it would have took him 2 hours to get home