Question

Can someone put a website to help me understand this?

Im sure its not hard I just don't know how to do it

Answer 1

67

Explanation:

Since the diagonals in a rectangle are congruent, AC=BD and

7x+18=10x-3

We need to separate x -- to do that, we can first subtract 7x from both sides, resulting in

18=3x-3

Next, add 3 to both sides to get

21=3x

Divide both sides by 3 to get

x=7

Then, we just plug x into 10x-3 to get BD = 7*10-3 = 67