Hi guys

Here is the question:

Jenny has 228 more marbles than jack. if bob gave each of them 133 marbles, she will have twice as many marbles as jack. How many marbles does jenny have?

I said (jn = jenny, jk = jack):

jn = jk+228

jn +133 = 2*jk

substitute jn-228 for jk in the 2nd equation:

jn +133= 2*(jn-228)

solve for jn:

jn=323

BUT why does this not work - it seems like it should???

jn = jk+228

Add 133 to jenny and jack:

jn +133= (jk+133)+228 = 2jk

jn+133 = jk+361 = 2jk

=> jk+361 =2jk

=> jk=361

so jn +133 = 361+228

and jn = 456

Help......please!