Can somebody help me please? I am having trouble answering this.

amber has allowed scientists to study dna that has been preserved over millions of years.

your answer is "the 1950's"

try using substitution:

x + y - 6 = x - y. (i'm not giving you the exact answer). since 0 = x - y, then sub 0 in the equation with x - y. combine your like terms, and then use inverse operations, and you'll have your answer.

: -)

geologic time scale (for gradpoint) =)