Equation

[halcyon days]

I am doing a quiz and the answers are about metals but this one I cannot get my head round any help appreciated

Solve this equation
50+ 82+ 29 + 51 =

Realise this adds up to 212 which is the boiling point of water but cannot link it to a metal answer.

[4candles]

Could it be based on the Periodic Table of Elements?

50 is Tin (Sn)
82 is Lead (Pb)
29 is Copper (Cu)
51 is Antimony (Sb)

Pewter is an alloy of these elements, or rather it was, the lead not being used now due to obvious health issues.

[halcyon days]

Thanks very much. Also for the excplanation.clever stuff.