What is the solution?

7x + 3 = 17

x = 2

x = 7

x = 20

x = 27

How do you use the elimination method for this question? explain, because i really want to understand!

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

Use this graph to find the cost of 6 show tickets