Answer:
207
Step-by-step explanation:
The sum to n terms of an arithmetic sequence is
[tex]S_{n}[/tex] = [tex]\frac{n}{2}[/tex] [ 2a₁ + (n - 1)d ]
where a₁ is the first term and d the common difference
Here a₁ = 37 and d = 34 - 37 = - 3 , thus
[tex]S_{18}[/tex] = [tex]\frac{18}{2}[/tex] [ (2 × 37) + (17 × - 3) ]
= 9( 74 - 51)
= 9 × 23
= 207
