A SAMPLE OF ANTIMONY, Ar=121.8, WAS ANALYSED AND WAS FOUND TO CONSIST OF 60% OF 121Sb AND ONE OTHER ISOTOPE. DETERMINE THE MASS NUMBER OF THE OTHER ISOTOPE IN THE SAMPLE OF ANTIMONY.

please help I'm really stuck,

Chemistry - bobpursley Saturday, September 30, 2017 at 10:41am
assume you have 100 grams. It becomes the overused algebra candy mixture problem.

60*121+40*X=121.8*100
solve for x

Chemistry - Dannau Saturday, January 6, 2018 at 7:01am
Thats wrong. The answer is 123

Chemistry - 0oooooooo0 today at 6:35am
How do you get that though

2 answers

I read somewhere the right answer is 123 but dont know how to get it and I tried Bobpursley equations but go -151.05 so I think that working out is wrong. Please help someone
I removed your incorrect answers to the math post. Please don't post answers for other students if you are not 100% sure and certainly not after a recognized tutor has replied. We remove incorrect and/or extraneous replies from other students.