Question 232750
Let {{{c}}} = grams of copper in bracelet
Let {{{g}}} = grams of gold in bracelet
given:
(1) {{{c + g = 238}}} g
(2) {{{g/19.3 + c/9 = 15}}} cm3
This is 2 equations and 2 unknowns, so it's solvable
Multiply both sides of (2) by {{{19.3*9 = 173.7}}}
(2) {{{9g + 19.3c = 2605.5}}}
Multiply both sides of (1) by {{{90}}} and subtract from (2)
(2) {{{90g + 193c = 26055}}}
(1) {{{-90g - 90c =- 21420}}}
{{{103c = 4635}}}
{{{c = 45}}}
45 grams of copper are mixed with the gold
check answer:
(1) {{{c + g = 238}}} 
{{{45 + g = 238}}}
{{{g = 193}}}
(2) {{{g/19.3 + c/9 = 15}}}
(2) {{{193/19.3 + 45/9 = 15}}}
{{{10 + 5 = 15}}}
OK