Why is it 85,680??(Linear Programming) But the given is 90,000X10^3 per day

Question

maximum of 90,000 10^3 cubic feet per day for its complexes.

but why did the das natural turn to 85,680?? Any suggestion. Thanks

This is my solution: 80(1200)+120(560)+140(540)+140(1200)+90(490)+70(160)+60(1280)+90(840) = 614,500 So I guess 90000X10^3 = 90000000

90000000 - 614,5500 = 89,385,.5500

What Formula did they use ??

Answer 1

Current natural gas usage = ( 1500*80*8 + 600*90*10 + 700*70*12 + 200*80*12 + 800*70*7 + 1500*80*18 + 1600*80*20 + 1400*60*14 ) / 100 = 85680

Nothing to do with linear-programming.