I believe that they typo meant 300 fossils of which 21% are snail shells.
Since % means per one hundred...
300(21/100)=63
Elmer has 63 fossilized snail shells.
To find the same value as 3 x 1/10 you first have to solve 3 x 1/10
so how to do this is you have to make 3 into a fraction
so to make 3 into a fraction you can put 3 as the numerator and 1 as the denominator
so you multiply

so 3/10 has the same value as 3x1/10
HOPE THIS HELPS!!!
Step-by-step explanation:
Here,
CDE+27+103+50+35=360(BEING THE SUM OF PIE CHART
CDE+215=360
CDE=360-215
CDE=145
(i amnt sure about answer)