Question

Find the four arithmetic means between -21 and -36.

Answer 1

maybe this example can help: http://www.algebra.com/algebra/homework/equations/Equations.faq.question.332361.html

Sorry, if it doesn't.

Answer 2

make it to (n+1) divisions..
\[d = \frac{b-a}{n+1}=\frac{-36-(-21)}{4+1}\]
and keep adding this d to -21 to get your numbers.
adding the fifth time should give you -36

Answer 3

-24,-27,-30 and -33