If −20 is the 15th term in an arithmetic sequence with a common difference of −7, what is the first term in the sequence?

-9x - 14

Step-by-step explanation:

Distribute (multiply) the 1/4 to everything in the parentheses.

1/4 * 4x = 1x or x       1/4 * -8 = -2

Then you distribute (multiply) the -2 to everything in the parentheses.

-2 * 5x  = -10x       -2 * 6 = -12

Then you put the equations together.

x - 2 - 10x - 12

Then you combine like terms.

x - 10x = -9x      -2 - 12 = -14

Finally you get your answer in simplest form.

-9x - 14