What is a1 of the arithmetic sequence for which a3=10 and a51=−182?

a₁ = 18

Step-by-step explanation:

The n th term of an arithmetic sequence is

= a₁ + (n - 1)d

where a₁ is the first term and d the common difference

Given a₃ = 10 and a₅₁ = - 182, then

a₁ + 2d = 10 → (1)

a₁ + 50d = - 182 → (2)

Subtract (1) from (2) term by term to eliminate a₁

48d = - 192 ( divide both sides by 48 )

d = - 4

Substitute d = - 4 into (1) and evaluate for a₁

a₁ + 2(- 4) = 10

a₁ - 8 = 10 ( add 8 to both sides )

a₁ = 18

the answers c

$25

step-by-step explanation:

25 - 4.50 = 20.5

20.5 / 2 = 10.25

10.25 + 10 = 20.25

20.25 - 12.50 = 7.75

therefore the answer is $25 as shown as the first number.