Help! (r varies jointly with s and t; r = 180 when...)

[oryanzmommy1]

i ran into a problem and i couldnt get it...i was clue less...i dont know how the problem is suppose to be set up or anything...HELP!!! here is the problem it gives me...

Suppose r varies jointly with s and t, and r=180 when s=3 and t=12. Find r when s=8 and t=20

 

[tkhunny]

Re: clue less people HELP!!!

r varies jointly with s and t

These words should ring in your head. Whenever you see them, don't even keep reading the problem. Stop! Write down "r = k*s*t". THEN go back and read the rest of the problem statement.

 

[oryanzmommy1]

ok thank you

 

[tkhunny]

The next step is to find 'k', the "constant of proportionality". This can be done by substituting all the values given in the problem statement. It MUST give you a complete set.

 

[oryanzmommy1]

ok thank you