1: Find the Totals:
The entire solution should use consistent
units of measurement: km, hours, and km/h. At
45 km/h Emma travels 15 km in 1/3 h. The rest
of the trip is therefore 30 km and takes 1/2 h.
Her total distance is 45 km and her total time
is 1/3 + 1/2 = 5/6 h. Thus, her average rate of
speed for the entire trip is 45 ÷ 5/6 = 54
2: Make a table:
good way to see this is to set up a table as shown
below, using the formula Rate × Time = Distance.
The shaded boxes contain the results of the computations,
multiplying across and adding down. We see that
the rate for the entire trip is 54 km/h.