Calculating a Percentage

Two questions:

In the forensic laboratory, a bullet found at a crime scene may be used as evidence in a trial if the percentage of three metals, usually lead, tin, and antimony, is a match to the composition of metals in a bullet from the suspect’s ammunition. If a bullet found at the crime scene contains 13.9 g of lead, 0.3 g of tin, and 0.9 g of antimony, what is the percentage of each metal in the bullet? Express your answers to the ones place.

A bullet seized from the suspect’s ammunition has a composition of lead 11.6 g, tin 0.5 g, and antimony 0.4 g.
a.   What is the percentage of each metal in the bullet? Express your answers to the ones place.
b.   Could the bullet removed from the suspect’s ammunition be considered as evidence that the suspect was at the crime scene?

Thanks