Question 675209
if you mean 20 , 30, and 40 percent of 80 and 1/4, 2/3, and 1/6 of 72, then you have:

{{{20}}}={{{20/100=1/5}}} 

{{{30}}} percent= {{{30/100=3/10}}}

{{{40}}} percent= {{{40/100=2/5}}}


of {{{80}}}:

{{{(1/5)80+(3/10)80+(2/5)80=(80/5)+(3*80/10)+(2*80/5)=(80/5)+(3*40/5)+(160/5)=(80+120+160)/5=360/5=72}}}



 and {{{(1/4)72+ (2/3)72 +(1/6)72=(72/4)+ (144/3) +(72/6)=(72*3/12)+ (144*4/12) +(72*2/12)=(216+576+144)/12=936/12=78}}}


OR, simply add percentage first: {{{20+30+40=90}}} percent and find {{{90}}} present of {{{80}}}:

{{{(90/100)80=(9/10)80=(9*80/10)=(9*40/5)=360/5=72}}}

do same with other one