Step-by-step explanation:
100% = 33,000 ft
1% = 100%/100 = 33000/100 = 330 ft
6% = 1% × 6 = 330 × 6 = 1980 ft
that means the plane has to go down 1980 ft to
33,000 - 1980 = 31,020 ft
and then it goes up by 5000 ft :
31,020 + 5000 = 36,020 ft
that is the final altitude.