No. 26,27 Tolong pake cara ya!

wanita = w
laki2 = p
p + w = 30
w = 30 - p

(70p + 75w) / 30 = 72
70p + 75(30-p) = 72×30
70p + 2250 - 75p = 2160
-5p = 2160 - 2250
-5p = -90
p = -90/-5 = 18 siswa