a) \(12.18+14.3-255:17=216+42-15=243\)
b) \(68+42.5-625:25=68+210-25=253\)
c) \(25.8-12.5+272:17-8=200-60+16-8=148\)
d) 125 : 25 + 14 - 142 : 71
= 5 + 14 - 2
= 17
e) 13 . 17 - 256 : 16 + 14 : 7 - 1
= 221 - 16 + 2 - 1
= 206
f) 324 : 18 - 289 : 17 + 18 : 3
= 18 - 17 + 6
= 7