Naturally occurring silicon exists as 3 isotopes: 28Si, 29Si, and 30Si, whose atomic masses are 27.9769, 28.9865, and 29.9838, respectively. The most abundant isotope is 28Si, which accounts for 92.23% of naturally occurring silicon. Given that the average atomic mass of silicon is 28.0855 amu, calculate the percentages of 29Si and 30Si in nature.

Please explain step by step

2 answers

28Si = 92.23% and 27.9769 amu
29Si = X% and 28.9865 amu
30Si = 100%-92.23%-X% = 7.77%-X and 29.9838 amu
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(0.9223*27.9769)+(X)(28.9865)+(0.0777)(29.9838 = 28.0955

Solve for X and 7.77-X
Answer?