Review

80/100 = m/ms ---------------------(01)

60/100 = (m-0.1)/ms----------------------(02)

35/100 = mo/ms

From (01) and (02) ,

ms = 0.5

mo = 0.175kg

m = 0.4

(m-0.1) = 0.3kg

Extra vapour mass that should be removed = 0.3-0.175

= 0.125kg

Answer - 03