chem

[sick mantle]

send help please

[hidden orbit]

1. multiply % by mass

20 x 90.5= 1810
21 x 0.25 = 5.25
22 x 9.25 = 203.5

2. add them together

1810 + 5.25 + 203.5
= 2018.75

3. divide by 100

2018.75/100 = 20.1875

you can check if your answer is right by comparing it with the one on your periodic table

[sick mantle]

omigod

thank you sm