Rewrite a. an = 19 - 7 (n-1)

Solution for an=19-7 (n-1) equation:

Simplifying

an = 19 + - 7 (n + - 1)

Reorder the terms:

an = 19 + - 7 (-1 + n)

an = 19 + (-1 * - 7 + n * - 7)

an = 19 + (7 + - 7n)

Combine like terms: 19 + 7 = 26

an = 26 + - 7n

Solving

an = 26 + - 7n

Solving for variable 'a'.

Move all terms containing a to the left, all other terms to the right.

Divide each side by 'n'.

a = 26n-1 + - 7

Simplifying

a = 26n-1 + - 7

Reorder the terms:

a = - 7 + 26n-1