a) 45*(16+25) = 45*41 = 1845
b) 121*(45*10-439) = 121*(450-439) = 121*11 = 1331
c) ((314:2-57)+25):25-5 = ((157-57)+25):25-5 = (100+25):25-5 = 125:25-5 = 5-5 = 0
d) (((120+2*15):75+4)*10^2-40*5):80 = (((120+30):75+4)*100-200):80 = ((150:75+4)*100-200):80 = ((2+4)*100-200):80 = (6*100-200):80 = (600-200):80 = 400:80 = 50