Answer :

well 4 is x = 100 and a =48 5 is y= 9.5 and x=90 cause if they are similar the sides should go into each other if multiplied or divided by a certain # in this case its4 is well 4 and 5 is 2 and angles usually stay the same however 6 s a little more complicated and i never got that kind...sorry ...hope that what i could do helps though :)
4
so there are two sides that are equal in both triangles so the 18ft coresponds to 72 so you multiply 72/18 by 25 and get 100 ft=x
triangle A is  has a bigger legnth and width but the angles stayed the same so angle 'a' is (if you look on the diagram of triangle X) 84 degrees

5.
in a rectangle each of the four angles are 90 degrees so x=90 degrees.
we notice that all of the  side legnths in the second triangle are equal so the rectangle is a square (a square is a special type of rectangle but a rectangle is not always a square) so the side legnths are equal so side y = 9.5 in.
6.
so f is a right angle because it's a rectangle which has, by definition, 4 right angles
so 12:q=6:5 so 12/q=6/5 we notice that the legnth is twice the width so 12:6=1:2 so q:5=1:2 or 10:5
 so q=10 cm

7.
so 3:4.8 and x:56 so 3/4.8=x/56 so you just invert them and multiply because 3/4 times 4/3=1 so then 3/4.8 times56/x=1
so 168/4.8x
x=35