①
(7.5+2.5)/0.25
= 10/0.25
= 40
②
210 - 18*4
= 210-72
= 138
③
5.4/18+12
= 0.3+12
= 12.3
④
2 / [8/5 * 25/24]
= 2 / (5/3)
= 6/5
⑤
2.25*1.8+1.25*0.28
= 2.25*(2-0.2) + 1.25*(0.2+0.08)
= 4.5 - 0.45 + 0.25 + 0.1
= 4.5 - 0.2 + 0.1
= 4.4