Hey there :)
To find the slope with <em>two points</em> we will need to use the equation 

( 3 , -20 ) ( 5 , 8 )
Here is what the equation should look like when replaced with the numbers (<em>it will be a fraction</em>) :

We know that <em>two negatives</em> cancel out and make a positive, so the numerator would actually be 8 + 20.
Solve the fraction and we get 
28 <em>divided</em> by 2 is 14. The slope is 14.
Answer:
$2.25
Step-by-step explanation:
Let "b" be the price of 1 brownie and "c" the price of 1 cookie.
At a bake sale, a student spent $11.00 buying 3 brownies and 5 cookies. Symbolicaly,
3 b + 5 c = 11.00 [1]
His friend spent $3.95 buying 1 brownie and 2 cookies. Symbolicaly,
1 b + 2 c = 3.95
b = 3.95 - 2c [2]
If we replace [2] in [1], we get
3 (3.95 - 2c) + 5 c = 11.00
11.85 - 6c + 5c = 11.00
c = 0.85
If we replace c = 0.85 in [2], we get
b = 3.95 - 2 (0.85) = 2.25
This is a subtraction expression.o evaluate, substitute 29 for the variable in the expression.to<span>evaluate the expression, subtract 31 from 29.</span>