"Using a system of linear equations to solve each problem?

I hate word problems and I do not understand them! please help me (or tell me how to) with these 2 problems! 1) Assume you are starting an office cleaning service. has spent $ 315 on the computer. To clean an office, using $ 4 worth of supplies. You charge $ 25 for the office. How many are there to clean the balance point? 2) On a canoe trip, paddling river Rita up (against the current) at an average speed of 2 km / h in relation to the riverbank. On the return journey downstream (with current), their average speed was 3 km / h. Rita Finding speed paddle in calm water and the velocity of the stream. Please help me! if you do, THANK YOU SO MUCH! :]

I LOVE problems at work, so I hope I can help. 1) Assume you are starting an office cleaning service. has spent $ 315 on the computer. To clean an office, using $ 4 worth of supplies. It charges $ 25 per office. How many are there to clean the balance point? Let x = # of offices to get clean 25/office, but go 4, so that net 21 21x = 315 x = 15 if you clean out of 15 offices that the equilibrium point ———————– — ———————– 2) On a canoe trip, paddling Rita upstream (against the current) at an average speed of 2 km / h on the riverbank. On the return journey downstream (with current), its average speed was 3 mi / h. Rita Finding speed paddle in calm water and the velocity of the stream. X = your pace, and current rate = x + y = rate at the current rate x = 3 = current counter = 2 x + y = 3 xy = 2 Add 2x = 5 x = 2.5 mph and 5 mph =.

Sturgeon River Michigan Paddle