berapa gram NaCl harus dilarutkan dalam 250 gr air agar memiliki titik beku -5,4° C (kf = 1,8) (Mr= 58,5)

wp = 250 gr
Tf = -5,4°C
Kf = 1,86
Mr = 58,5
wt = ......................?

ΔTf = wt/Mr x 1000/wp x Kf
5,4 = wt/58,5 x 1000/250 x 1,86
5,4 x 58,5 = wt x 7,44
315,9 = wt x 7,44
wt = 315,9/7,44
wt = 42,46 gram