We find the length of AD using the similarity of right triangle property. See image attached.
AD² = BD × CD
AD² = 9 × 36
AD² = 324
AD² = 18²
AD = 18
The length of AD is 18 units
Answer and workings in the attachment below.
500 in 2:3 is saying that there are five different parts (2 + 3)
This means that 500 needs to be split into five, which is 100.
After that all you need to do is put 2 'sections' on one side and 3 on the other.
For example, 2 : 3 = 2( x 100) : 3( x 100)
= 200 : 300