Please help.
Algebra.

The brain volumes (cm cubed) of 50 brains vary from a low of 904 cm cubed to a high of 1488 cm cubed. use the range rule of thumb to estimate the standard deviation s and compare the result to the exact standard deviation of 175.5 cm cubed, assuming the estimate is accurate if it is within 15 cm cubed

Solve the equation x/4 - 5= -8 -27 -12 -7 12

What is the solution to the equation? k/6.4=8.7 2.3 5.568 15.1 55.68