Can some help me find the answers to all of these just not number 3

Kapil needed to buy a long wooden beam. he went to two sawmills that each charge an initial fee plus an additional fee for each meter of wood. the following equation gives the price (in dollars) of a wooden beam from the first sawmill as a function of its length (in meters). p = 5+20xp=5+20x

Write numerical coefficient of y² in the expression 2x² - 15xy – 7y²

What is the correlation coefficient between the variables? round to three decimal places. enter your answer in the box