I need help with two math questions?

1) Solve a(b-c)=a/b for c. *The answer I got was c=a/b-b. Is this right?



2)The average cost of tuition and fees at a four-year college was $3,356 for the year 1999-2000. For the year 1997-1998 the average cost was $3,111. Find the rate of change between the year 1997-1998 and the year 1999-2000. *I can't remember how to do this one, because it was from about 5 chapters ago. If you could refresh my memory with a formula or something like that, I would appreciate it very much! =)



Thank you sooo much in advance!I need help with two math questions?
You are correct; mostly; with the First one, excepts it is a^2, not just a. I can't help you off hand with the second,although I would presume it to be the average change in cost per year. Hope this helps.I need help with two math questions?
For the first one i got -c = (a+a) / a.....................which i think would reduce to -c = a. I can't help with the second problem though because i don't get back into algebra until next year. Good luck!