Find the length of side a.

Marlow is comparing the prices of two trucks rental compaines company a charges $3 per hour and an addtional $75 as serivce charges company b charges $2 per hour and an additional $85 as serivce charges

Acyclist bike x distance at 10 miles per hour .and returns over the same path at 8 miles per hour.what is the cyclist average rate for the round trip in miles per hour ?

Which property was used to simplify the expression? 3c+9 +4c=3c+4c+9