While driving on the highway, fiona averages 60 miles per hour. in the city, she averages 30 miles per hour. on a trip to her grandmother's house, fiona drives 312 hours on the highway and 112 hours in the city. what is fiona's average speed for the entire trip to her grandmother's house? i dont know the answer

1.       Fiona drives 60 miles per hour on the Highway
And drives 30 miles per hour on the City.
She got a total of 312 hours in the highway and 112 hours in the city
Find the average speed of Fiona:
Formula of Speed
=> S = d / t
Let H be the distance in Highways
and Let C be the distance in City
=> H = 60 x 312
=> H = 18 720
=> C = 30 x 112
=> C = 3360
=> Total distance = 18 720 + 3 360
=> 22 080 miles
Let’s find the total time
=> H + C
=> 312 + 112
=> 424 hours

Speed = 22 080 / 424
S = 52.1 miles per hour