tolong kerjakan cepet +caranya besok di kumpul.....

7) V = plt
385=11×5×(3+x)
385=55×(3+x)
3+x= 385/55
3+x=7
x=7-3
x=4
8)cat yg diperlukan=[2pt + 2lt] / 40
=[2×20×10 + 2×12×10] / 40
=[400 + 240] / 40
= 640 / 40
= 16 kaleng cat
9) tinggi limas(tl)=25-20=5cm
t1=akar[(tl)^2+(1/2×p)^2]
=akar[5^2+(1/2×25)^2]
=akar[5^2+12,5^2]
=akar[25+156,25]
=akar 181,25=13,5 cm
t2=akar[(tl)^2+(1/2×l)^2]
=akar[5^2+(1/2×8)^2]
=akar[5^2+4^2]
=akar[25+16]
=akar 41 = 6,4 cm
L permukaan balok=pl+2pt+2lt
=25×8+2×25×20+2×8×20
=200+1000+320
=1520 cm^2
L permukaan limas=2×1/2pt2+2×1/2lt1
=2×1/2×25×6,4 + 2×1/2×8×13,5
=160+108
=268 cm^2
L seluruh permukaan bangun itu =1520+268
=1788 cm^2