Parker ran 100 meters,1 kilometer, and 5,000 centimeters. how many meters did he run all together.

It already tells you that he ran 100 meters so what you need to do is convert kilometer to meter and centimeter to meter.
1 kilometer is is 1000 meters. 1 meter is 100 centimeters.
So 5000 centimeters is 50 meters.

Add 100 + 50 + 1000 =
1,150 meters :)

Well,  1 km = 1000 mts , and 1 cm = 0.01 mts

so, parker ran = 100 mts + 1000 mts + 50 mts  = 1150 meters 

hope it helped atleast a bit :)

When rates are expressed as a quantity of 1, such as 2 feet per second or 5 miles per hour, they are called unit rates. if you have a multiple-unit rate such as 120 students for every 3 buses, and want to find the single-unit rate, write a ratio equal to the multiple-unit rate with 1 as the second term.