Answer:
S₁₅ = 645
Step-by-step explanation:
The sum to n terms of an arithmetic sequence is
=
[ 2a₁ + (n - 1)d ]
where a₁ is the first term and d the common difference
Using the nth term formula = 5n + 3 , then
a₁ = 5(1) + 3 = 5 + 3 = 8
a₂ = 5(2) + 3 = 10 + 3 = 13 , then
d = a₂ - a₁ = 13 - 8 = 5
Thus
S₁₅ = [ (2 × 8) + (14 × 5) ]
= 7.5( 16 + 70)
= 7.5 × 86
= 645
Answer:
13 pieces
Step-by-step explanation:
We are given that each pie was cut into 8 pieces .
therefore 1 pie is equal to 8 pieces
1 pie = 8 pieces
Lonna gave 13/8 pie to her neighbor .
So multiply both sides with 13/8 in the above equation in order to make the right side into 13/8 pie and to find the corresponding number of pieces .
1× pie=8×
pieces
pie = 13 pieces