Resposta :
an=a1+(n-1).r
an=8+(18-1).4
an=8+17.4
an=8+64
an=72
sn=(a1+an)n/2
s18=(8+72)18/2
s18=80.18/2
s18=1440/2
s18=720 é o total de assentos
an=8+(18-1).4
an=8+17.4
an=8+64
an=72
sn=(a1+an)n/2
s18=(8+72)18/2
s18=80.18/2
s18=1440/2
s18=720 é o total de assentos