30% x X + X x 0.5 + X + 3/4 x X =15.3
X x (30% + 0.5 + 1 +3/4) =15.3
X x 2.55=15.3
X=15.3 x 2.55
X =39.015
40 x 1.6 + 1.6 x 4.2 + 1600 x 0.018
=1.6 x (40+4.2) + 28.8
=1.6 x 44.2 +28.8
=99.52
nhớ k 8 cai nha
40*1.6+1.6*4.2+1600*0.018
=64+6.72+28.8
=70.72+28.8
=99.52