How would you write an algebraic equation for this problem?

3J=E
2K=J
J+ K+E=240

Let x be the number of stickers Ethan got.
Then James got 3x stickers
And Ken got 6x stickers.

x + 3x + 6x = 240
10x = 240
x = 24

Ken received 6x = 6*24 = 144 stickers.

Hope that helps!

James, Ken, and Ethan shared 240 stickers.... ==> J + K + E = 240

James got 3 times as many as Ethan............... ==> J = 3*E

Ken got 2 times as many as James.................. ==> K = 2*J

So 3*E + 2*J + E = 240
==> 3*E + 2*(3*E) + E = 240
==> 3*E + 6*E + E = 240
==> 10*E = 240
==> E = 24

So J = 3*24 = 72 and
K = 2*72 = 144

144+72+24 = 240

Understand the problem.  What is it about?  Who is involved?  What are we trying to figure out?  What do we know?
Then (only after you understand) decide on what variables to use.
Let J be the number of sticker Jim has.  Let K be the number Ken has.  Let E be the number Ethan has.
We know that J + K + E = 240.
We also know J = 3E  and K = 2 J

You always have the right to replace something with its equivalent. Since I know that J = 3E  I can replace the J in K = 2J   to get K = 2(3E) or, simply K = 6E.   Now I can run over to the first equation and make some replacements for K and J

 J + K + E = 240 ---> 3E + 6E + E = 240  or simply 10E = 240.  Can you tell me how many stickers Ethan has?  If you can do that, you can also tell me how many stickers Ken and Jim have, as well.

To check if your answer is correct, see what they add up to.

I know the question was 'How many did Ken receive.'  Notice, you can figure out how many each PERSON received.  If your teacher has 'issues' with you figuring out to much (Heaven forbid you ever learn too much or get too smart!) the just respond with the answer for Ken and keep the rest up your sleeve.  In a problemlike this, you cannot check your answer unless you do solve for the other folks, as well.

Does this help?

K + J + E = 240

so K = 240 - J - E

so K = 240 - K/2 - K/6  
(Ken had twice as many as James and 6 times as many as Ethan)