Duplicate 0.50 g samples of a finely powdered gold ore are digested in an HCl/HNO3 mix and evaporated to dryness. Each sample is then treated with an additional 15 mL of HCl and diluted with an additional 40 mL of water. To one sample a 1.00 ml volume of a gold standard containing 5.0 ug/mL of gold is then added. Both samples are then treated with 5 mL of concentrated HBr to produce a gold bromide complex, and this is then extracted into 5 mL of methylisobutyl ketone. The atomic absorption signals were A=0.22 for the unspiked sample and 0.37 for the sample spiked with the additional gold standard. Assuming that the signal is linear over the measured absorptions, what is the concentration of gold in the original sample in ug/g?