Question 825685
let the distance be x

time taken by Sue = x/42

time taken by Bob = x/58

time Sue = Time Bob + 4 hours

x/42= x/58 +4

x/42-x/58 = 4

58x-42x= 4*58*42

16x= 4*58*42

x=4*58*42/16

x=29*21

x= 609 miles distance to grandpa's house

You can calculate time by the formula t= d/r for each of them