125-75=50 (m3)

145- 125=20 (m3)

75*2.5+50*2.75+20*3

= 187.5+ 137.5+60

=385 (yuan)

A: The cost should be 385 yuan.

(2)

75*2*2.5+( 175-75*2)*2.75 ( 125-75)*2.75+( 175- 125+75)*2.5

=75*5+25*2.75 =50*2.75+ 125*2.5

=375+68.75 = 137.5+3 12.5

=433.75 yuan =450 yuan

433.75 & lt455 450 & lt455

(455-450)/(3-2.5)= 5/0.5 = 10(m3)

February:125+10 =135 (m3)

March: 175- 135=40 (m3)

Answer: The gas consumption in February is 135 cubic meters, and that in March is 40 cubic meters.