Y + 1 = -3(x - 5)
y + 1 = -3x + 15
y = -3x + 15 - 1
y = -3x + 14 <== or f(x) = -3x + 14
Lan wants to run less than 7/12 miles. It says to find out a fraction with a denominator of 4 and which is less than 7/12.
Let's assume the required fraction to be x/4 such that x/4 is less than 7/12.

So we must have multiples of 3's that should be less than 7, we have only two choices 3 < 7 or 6 < 7.
It means x = 1 or x = 2, and the required fraction would be 1/4 or 2/4.
2/4 is simplified to 1/2 and the question says to have denominator 4.
Hence, final answer is 1/4
Since DC = 12, then EF also = 12.
Both AD and BC are indicated to be the same .
So AE = (24 - 12) / 2 = 12/2 = 6
Now you have a right triangle with height DE = 8 and base AE = 6
Using the Pythagorean Theorem we can now find AD:
AD = √(8^2 + 6^2)
AD = √(64 + 36)
AD =√100
AD = 10
X + k y = 1
k x + y = 1 / * ( - k )
----------------
x + k y = 1
- k² x - k y = - k
--------------------
x - k² x = 1 - k
x ( 1 - k² ) = 1 - k
x = ( 1 - k ) / ( 1 - k² ) = ( 1 - k ) / ( 1 - k ) ( 1 + k )
y = 1 - k( 1 - k )/( 1 - k² )
y = ( 1 - k ) / ( 1 - k² ) = ( 1 - k ) / ( 1 - k ) ( 1 + k )
a ) For k = - 1 this system has no solution.
b ) For k ≠ - 1 and k ≠ 1, the system has unique solution:
( x , y ) = ( 1/ (1 + k) , 1/( 1 + k ) ).
c ) For k = 1, there are infinitely many solutions.