Refer to figure.
The given tables list the TAS (kt) in fuel consumption (gal/H or GPH) depending on pressure altitude and ISA deviation. We therefore first have to find the pressure altitude.

We are flying at an altitude (QNH altitude) of 8 500 ft with a QNH of 1030 hPa. The altitude difference is equal to
1013 hPa – 1030 hPa = -17 hPa
-17 hPa x 30 ft/hPa = -510 ft

Our pressure altitude is then equal to
8500 ft – 510 ft = 7990 ft ≈ 8000 ft

We therefore have to use the lower table for this question.

The three columns give TAS and GPH for ISA deviations of -30°C, 0°C and +30°C. Our OAT is given to be ISA +15°C, which means we assume a value halfway between ISA and ISA +30°C.

The line for an RPM of 2300 and MAP of 22 holds TAS values of 167 kt and 164 kt, so we expect approximately 165 kt.

The GPH is between 12.4 and 11.5, which roughly gives 12 GPH.