Answer:
Option A) 585
Step-by-step explanation:
a1 = 5(1)-1 = 4
a2 = 5(2)-1 = 9
d = a2 - a1 = 9 - 4 = 5
n = 15
[tex]\frac{n}{2}(2a+(n-1)d)[/tex]
= [tex]\frac{15}{2}(2(4)+(15-1)5)[/tex]
= [tex] \frac{15}{2}(8+(14)5)\\= \frac{15}{2}(8+70)\\= 15 × 39\\= 585[/tex]
