3.6*1994 2/5+2006.9*6 2/5
=3.6*1994.4+2006.9*6.4
=3.6*(2000-5.6)+(2000+6.9)*6.4
=(3.6+6.4)*2000-3.6*5.6+6.9*6.4
=10*2000+6.9*6.4-3.6*5.6
=20000+0.3*23*0.8*8-0.3*12*0.8*7
=20000+0.3*0.8*(23*8-12*7)
=20000+0.24*(184-84)

=20000+24
=20024