Math problems pls help meee

I am studying for a test on the review sheet there are problems similar to what will be on the test and i dont understand some can someone help me i dont just need answers i need explanation so that i will do well on the test

The vertices of a sqare P ( the p is drawn in a sqare) are (0,0) (3,0) (4,4) and (x,4). A value of x may be
1
2
3
4

Write a equation of the line passing through the origin and perpendicular to y=-3/4x+7

In p (the letter p is in a sqare) abcd, ab=5x-4 and cd=2x+14 find x

1) I have no idea (sorry).

2) To get an equation of a line perpendicular to y=-3/4x+7, you know that the new slope will be the opposite reciprocal of -3/4 (which is 4/3), then plug in the point (0,0) (the origin) to find the y-intercept.
y=4/3x+b
0=4/3(0)+b
b=0

So the equation of the line perpendicular to y=-3/4x+7 that passes through the origin is y=4/3x.

*TIP - If a line passes through the origin, it's y-intercept is always 0, just like this case. So technically, you didn't need to solve for b since we know it's zero.

3) Since figure ABCD is a square, all its sides are of equal length.
So 5x-4=2x+14. Just solve for x.

5x-4=2x+14
3x-4=14
3x=18
x=6 - - - - - Final Answer