It is y = 12x + 20.
You start with 20 as the y-intercept because that is the starting amount that you paid. The constant rate of change is 12 dollars per book. So, 12 time however many books written as 12x. Hope that helps! :)
No steps are wrong. To solve this equation, you need to isolate the y. So, you would add 4.6 to both sides to cancel out the 4.6 on the right side and isolate the y.
(1) 6 1/3 = 76/12
2 3/4 = 33/12
___________+
109/12
divide and get 9 1/12
-----------------------------------
(2)3 1/2 = 43/12
5 1/2 = 66/12
*from first answer* 109/12
add and you get 218/12
divide and get the answer 18 1/6
Hope this helps you!
Answer:

General Formulas and Concepts:
<u>Pre-Alg</u>
- Order of Operations: BPEMDAS
<u>Algebra I</u>
- Slope Formula:

Step-by-step explanation:
<u>Step 1: Define</u>
Point (40, 3000)
Point (60, 4000)
<u>Step 2: Find slope </u><em><u>m</u></em>
- Substitute:

- Subtract:

- Divide:

9514 1404 393
Answer:
3.61 seconds
Step-by-step explanation:
The bird starts 50 feet in the air, so will come down to a height of 40 feet after 3.61 seconds.
We want to solve h = 40.
40 = -16t^2 +55t +50
16t^2 -55t -10 = 0
t = (55 +√(55^2 -4(16)(-10)))/(2(16)) = (55 + √3665)/32 ≈ 3.61060
The bird will be 40 ft above the ground the first time after about 3.61 seconds.