Question 1023514
Let price / kg of gold = {{{ g }}}
Let price / kg of silver = {{{ s }}}
Let price / kg of platinum = {{{ p }}}
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(1) {{{ 1*s = 1.6*g
(2) {{{ 1*g = 1.25p }}}
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(1) {{{ 1*s = 1.6g }}}
and
(2) {{{ 1.6*( 1*g ) = 1.6*( 1.25p ) }}}
(2) {{{ 1.6g = 2p }}}
And, from (1)
{{{ 1*s = 2p }}}
So, 2 kg of platinum has the 
same value as 1 kg of silver
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Note that the above equation is:
[ value of silver ] = [ value of platinum ]