45.8% is the change from 345 to 503
Calculation steps:
[( 503 - 345 ) ÷ 345] x 100 = 45.8%
Formula
Percentage change = [(503 - 345) / 345] x 100
Subtract the new number by the original number
503 - 345 = 158
158 ÷ 345 = 0.4579710144927536
0.4579710144927536 x 100 = 45.8%