Johnny travelled at 32 mph for 30 min.
Then, he travelled at 48 mph for 45 min.
We need to find the total distance he travelled.
We notice that he travelled at two different speeds.
Then we will find the distance he travelled at each speed, then we will find the total speed.
Let the first distance be D1 and the second distance be D2
==> We know that D = speed(mph) * time (hour)
==> time = 30 min = (1/2) hour
==> D1 = 32* (1/2) = 16 miles
Now we will calculate D2.
==> D2 = speed * time
45 min = (3/4) hour
==> D2 = 48*3/4 = 36 miles.
Then, the total distance he travelled is:
D = D1 + D2 = 16 + 36 = 52 miles.
Then the total distance is 52 miles.