Business Pre-Calc Help

Question

I have done this problem two times now and got it wrong both times, I am not sure where I am going wrong though:

The water level was 15 milliliters before adding the chain, and 20 milliliters after adding the chain. When I weighed the chain, its mass was 76.8 grams.

I believe the chain is solid metal (not gold plated), but is probably a blend of gold and other metals. I looked up that gold has a density of 19.3 g/ml, while the other metals like silver and copper usually blended with gold have a combined density of about 9.7 g/ml.

Determine what percentage of the chain is gold, by mass, to at least 1 decimal place?

I have:

G=Gold

B= Blended material

Water Level Difference 20ml-15ml= 5ml

G + B= 5 = (G=5-B)

19.3G + 9.7B= 76.8

19.3(5-B)+9.7B=76.8

96.5-19.3B+9.7B=76.8

96.5-9.6B=76.8

-9.6B= -19.7

B=2.052083333

G+2.052083333+5

G= 2.947916667

2.94791667/76.8 (100%) = 3.83843316

BUT that is wrong?

Answer 1

In this equation I think there is a unit problem.

19.3G + 9.7B= 76.8

The units are

g/ml + g/ml = g

The units are the same, which is a problem. I think if you do 76.8 g/5 ml that could fix it.