The weight of copper is 8 1/10 in the gram.
I add 2x + 3x to get 13 1/2 to find what x is to multiply back into the ratio to find the weight of copper.
So the equation is 5x=13 1/2
Solving it we get x=27/10.
Now we multiply 27/10 * 3 to find the weight of copper. The answer is 81/10, simplifying into 8 1/10. This means that the weight of Zinc is 5 2/5, we get this by subtracting 13 1/2 to 8 1/10.
Hope this helps!
