-0,5(1-3n)+4(0,2n-0,1)-(0,1-0,7n) если n=0,21
-0,5+1,5n+0.8n-0.4-0.1+0.7n -0.5+3n-0.4-0.1 -0.5+(3*0.21)-0.4-0.1 -0.5-0.63-0.4-0.1=0.63
спасибо )