Simplify this variable expression -5b + 7a - 7b + 12a

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

Given a: b and b: c, find a: b: c. write the ratio in simplest form. a: b=6: 10 and b: c=21: 33

The serenity and the mystic are sail boats. the serenity and the mystic start at the same point and travel away from each other in opposite directions. the serenity travels at 16 mph and the mystic travels at 19 mph. how far apart will they be in 3 hours?