We will use the Least Common Multiple or LCM. Since we are looking for same number of packages to be shipped.
Sarah’s trucks carries 18 while Ryan’s truck only carries 10.
Solution:
10 = 10, 20, 30, 40, 80, 90
18 = 18, 36, 54, 72, 90
The LCM is 90. Therefore, 90 is the minimum number of packages each must have shipped.