part A)
we know that for every 1000 ft the temperature drops by 1.3.
so after 1000ft up it went down by 1.3(1)
2000ft up it went down by 1.3(2) or 2.6
3000ft up it went down by 1.3(3) or 3.9
after 10000 up it went down by 1.3(10) or 13.
part B)
well, the current temperature on the ground where the plane is sitting is -2.8°F, after 10000ft it dropped by 13°, so the temperature will just be -2.8 - 13 = -15.8°F.