Respuesta :

naǫ
[tex]A=\frac{a+b}{2} h[/tex]
A - area
h - height
a+b - sum of its top and bottom sides

[tex]20=\frac{a+b}{2} \cdot 5 \\ 4 = \frac{a+b}{2} \\ a+b=8[/tex]

The sum of its top and bottom sides is 8 cm.