The slopes of parallel lines are exactly the same opposites reciprocals

What value of x is in the solution set of –5x – 15 > 10 + 20x?

Iam trying to solve a linear equation for the shoe size of someone 84" tall taking into consideration example 1 is 69" tall with a shoe size of 9 and example 2 is 72 inches tall with a shoe size of 11. i understand that the equation should be y=mx+b and that on the graph the answer is (3,2) but i just don't understand how to create the equation to solve for 84-inches and 60-inches tall questions. after two days, i need .

Find the number of real number solutions for the equation. x2 + 5x + 7 = 0 0 cannot be determined 1 2