Please help! This really doesn't make sense to me. I NEED HELP!!!!

Find the scale of the two similar sides with known dimensions:
45/27 = 1 2/3
Figure A is 1 2/3 times larger than B. Now multiply the similar side of B to find x:
x = 18 x 1 2/3
x = 30
Answer: x = 30
Answer: 30
Step-by-step explanation:
(This is a similarity question)
So,
X/18 = 45/27
Then cross multiplication
X= 45×18/ 27
X= 30