C. 427
The median is the middle number of all the data
Since there is an even number of data points the median is in between the middle two data points (434 and 420)
To find this: 434-420=14
14/2=7
434-7=427
420+7=427
Simple
like when you buy something at the store. the person is selling products to you
ASA postulate because theres two angles and the side in the middle