Isolate the n. First, multiply 8 to both sides
40(8) = (-5n/8)(8)
40(8) = -5n
Multiply.
320 = -5n
Isolate the n. Note the equal sign. What you do to one side, you do to the other. Divide -5 from both sides
(320)/-5 = (-5n)/-5
n = 320/-5
n = -64
-64 is your answer for n
hope this helps