text: (4,-5), m=-1/2?   we know that the equation of a straight line is y=mx+c.now as the straight passes through (4,-5) ,the value of x=4 and y=-5 would satisfy the equarion.putting these values in the equation,w get -5=4(-1/2)+c or -5=-2+c => c=-7 therefore,the equation is y=-(1/2)x-7 [if you like you may multiply all the terms by 2 to make it 2y=-x-14]