Answer:
45
Step-by-step explanation:
20. 20+12=32. that's math(s).
Sum of the terms of the series is
Sn = n/2 ( a1+an )
we have n= 6 , a1= 17, an = 57
so Sn = 6/2 ( 17+57) = 3(74) = 222
Note that 5x appears on both sides of this equation. Delete 5x from each side. This leaves us with 3x = 15/2. Dividing both sides by 3 results in x = 5/2 (ans)
