Trapezoidal Prism
It is a prism with 2 bases of shape trapezoid
First 1/5 is equivalent to 20% so to get 20% of both of them multiply by .2. so 400×.2=80 and 90×.2=18

=

equals
k = 15.6
First, simplify

to 1.2. Your problem should look like:

= 1.2
Second, multiply both sides by 13. Your problem should look like: k = 15.6, which is the answer.
Add subtraction multiplication and division