The line AB has equation 7𝑥 + 2𝑦 = 11

$7𝑥 + 2𝑦 = 11$

$<=> 𝑦 =- \frac{7x}{2} + \frac{11}{2}$

We will call $λ=-7/2$ is the coefficient of x 

so every parallel line to AB will have $λ=-7/2$

lines have type : $y-y1=λ(x-x1)$ We want coordinates (-5, 25/2 ) 

so x1=-5 and y1=(25/2) 

$y-(\frac{25}{2})=-\frac{7}{2}(x-(-5))$

$y=-\frac{7}{2}(x+5))+\frac{25}{2}$

$y=-\frac{7}{2}x-\frac{35}{2}+\frac{25}{2}$

$y=-\frac{7}{2}x-\frac{10}{2}$

$7x+ 2y=-10$

"Given the line AB passes through the point (k, k+1) find the value of the constant k."

This means  x= k, y=k+1 verify the equation 7𝑥 + 2𝑦 = 11 

So 

$7k+2(k+1)=11$

$7k+2k+2=11$

$9k=9$

so $k=1$ 

Finally the point (k, k+1) is (1,2) 

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