Use proportions for all of them, for #1 use the proportion 12/30 = 9/a based on corresponding sides and then cross multiply. a=22.5 For #2 use the proportion y/35 = 64/40 based on corresponding sides and then cross multiply, y=56 For #3 use the proportion 42/? = 54/36 and then cross multiply, ?=28
Answer:
<h2>S.A. = 234 mm²</h2>
Step-by-step explanation:
The formula of a surface area of a rectangular prism:

l - length
w - width
h - height
We have l = 15 mm, w = 3 mm, h = 4 mm. Substitute:
