0,5=5/10=>1/2
0,1=1/10=>1/10
0.3=>3/10
2,1=>21/10
0.4=>4/10
(1/2+1/10)³:3/10+21/10×4/10
=(5/10+1/10)³:3/10+21/10×4/10
=(6/10)³:3/10+21/10×4/10
=216/1000:3/10+21/10×4/10
=216/1000:10/3+84/100
=72/100+84/100
=156/100=1,56