1) (12078+2106*16:2):2= 14463
2106*16=33696
33696:2=16848
12078+16848=28926
28926:2=14463
2) (468093-284052) :3-146*309=16233
468093-284052=184041
184041:3=61347
146*309=45114
61347-45114=16233
3) (62500:100*128)-57999=22001
62500:100=625
625*128=80000
80000-57999=22001
4) 83000-8691*7+506*89=67197
8691*7=60837
506*89=45034
83000-60837=22163
22163+45034=67197