0.1× 2 = 0.2m2.

0.08× 2 = 0.16m2

(0.2+0. 16)×2 = 0.72 m2- surface area of water-saving pipeline

Section 25

25× 0.72 = 18m2

Eight questions

9×7=63 Roof

(7×3+9×3)×2=96 walls

96-29.6+63= 129.4 square meters, that is, these are the areas to be drawn after the blackboards of doors and windows are removed.

129.4×0.2=25.88 requires at least 25.88kg.

I hope my answer is helpful to you! I wish you progress in your study! ! ! ! ! ! ! !