Usually I just use slope calculator hope that helps
Equation of a line in slope-intercept form:

m is the slope
b is the y-intercept
As you have the slope (m= -4) and a point (6,1) you use it in the equation above to find the y-intercept, as follow:
(6,1) x=6 y=1
m= -4

Solve b:

Then, the equation of the given line in slope-intercept form is:
Find the number of miles driven by subtracting the odometer readings:
74545 - 74233 = 312 miles driven.
Divide miles driven by gallons of gas used:
312 / 9 = 34.66 = 35 miles per gallon.
Answer:
The palm tree is 12 m tall.
Step-by-step explanation:
1. The first to see is to consider this as triangle formed by the palm tree, the shadow, and the line from the top of the tree to the tip of the shadow to the tip the palm.
2. Assign variables to each distance in the triangle
Palm length= X
Shadow length= y
line from the top of the tree to the tip of the shadow to the tip the palm = Z
3. Describe the equation, reading the text:
(1) y=x-7
(2) z=x+1
(3)
(this last one is from pitagoras theorem)
4. We solve the system:
{y = x - 7, z = x + 1, z^2 = x^2 + y^2}
Solutions
x = 4, y = -3, z = 5
x = 12, y = 5, z = 13
Since the distance can't be negative. The answer is the palm tree is 12 meters tall.
https://www.wolframalpha.com/input/?i=y%3Dx-7%3B+z%3Dx%2B1%3Bz%5E2%3Dx%5E2%2By%5E2