I need help with this, please. Any advice would be appreciated.

see explanation

Step-by-step explanation:

The sum to n terms of an arithmetic sequence is

= [ 2a₁ + (n - 1)d ]

where a₁ is the initial value and d the common difference

Given

= [ 10 + (n - 1)3 ]

Then by comparison

2a₁ = 10 ( divide both sides by 2 )

a₁ = 4 ← initial value

and d = 3 ← common difference

Thus

= [ 10 + (7 × 3) ]

   = 4(10 + 21)

   = 4 × 31

   = 124

the equation cos(35) =a/25 can be used to find the length of bc what is the length of bc? round to the nearest tenth

step-by-step explanation:

a; x = 0.5

step-by-step explanation:

-10x = -5

x = 0.5