The summation of a piechart is 360°.  To get the figure for manufacturing sector we simply add the figures for oil, agriculture and mining sector and minus it from 360. Thus we have;

160 + 90 + 30 = 280
360 - 280 = 80
Manufacturing sector = 80°

The difference between Oil sector and manufacturing sector =

Oil sector = \(\frac{160}{360}\) x 100 = 44.44% 
0.444 x 60,000,000,000 = 26,640,000,000

Manufacturing sector = \(\frac{80}{360}\) x 100 = 22.22%
 0.222 x 60,000,000,00 = 13,320,000,000

Difference 26,640,000,000 - 13,320,000,000 = 13,320,000,000