Why are you stuck, you are given the C_14 concentration in the sample 190ng/g, you are given a graph of the age zero C_14 concentration in the same units, and the half-life of C_14.

Correct the data in the graph from age zero concentration to that today, then look up the tapestries C_14 concentration on the resulting graph to get the age of the sample.

(By the way it is obviously no more than 500 years old)

CB