help on questions for math methods unit 3 &4 please urgent i tried but no luck

[Zahta]

ABCD is a quadrilateral with angle ABC a right angle. D lies on  the perpendicular bisector of AB. The coordinates  of A and B are (7,2) abd (2,5) respectively. The equation of the line is AD is y=4x-26

a) the equation of the perpendicular bisector of line segment AB.
b)Find the coordinates of point D
c) find the gradient of line BC
d)Find the value of the second coordinate C of the point (8,c)
e)Find the aread of quadrilateral ABCD






Another question

if A=(-4,6) and B=(6,-7) find.
a) the coordinates of the midpoint of AB
b)the length of AB
c)the distance between A and B
d) The equation of AB
e) The equation of the perpendicular bisector of AB
f) the coordinates of P, where P element of Ab and AP:PB=3:1
g) the coordinates of P,where P element of AB and AP:AB=3:1


A triangle ABC with A(1,1) and B(-1,4). The gradients AB, AC and BC are -3m,3m and m respectively.
a) find the value of m
b) find the coordiantes of C
 c) show that AC=2AB


Solve the following pairs of simulataneous equations  for x and y.
(a+b)x+cy=bc
(b+c)y+ax=-ab


Write s in terms of a in the following
as=a+h
h+ah=1

Find the values of b & C for which the equation  x+5y=4 and 2x+by=c have:
a)unique solution   b) an infinite soln and no solutions



Thank you so much on who ever can help me i really did try them all but i could not get them would appreciate anyones help i really need to understand them all

[Somye]

a) gradient of AB = (5-2)/(2-7) = -3/5
therefore grad of perpendicular bisector = -1/(-3/5) = 5/3
as it's a bisector the line has a point halfway on the line AB therefore [(7+2/2),(2+5/2)] = (9/2,7/2)
sub in values into a y=mx+c and c = -4 therefore eqn = y=(5/3)x-4
b)make 4x-26=5/3x-4 and solve for x which = 66/7
c) bc is perpendicular to AB therefore grad also = 5/3
point on line is at A and so sub in (7,2) and that gives you c = -29/3

... those numbers seem too ugly, but I'm pretty sure that's the logic that goes into it