Answer: 1:5
Step-by-step explanation:
Given: The cost of every mirror is proportional to the cube of the mirror's radius.
i.e. 
Their largest mirrors have radii of 5 meters and their smallest mirrors have radii of 1 meter.
Then,

The ratio of the total cost of 25 of the company's smallest mirrors to the cost of one of the company's largest mirrors will be:

Hence, the ratio of the total cost of 25 of the company's smallest mirrors to the cost of one of the company's largest mirrors = 1:5 .
Diagonals of a rect. are equal...
diagonals bisect each each other...
from these two properties we get ,
4x-12 = 1/2 (7x-18)
2 (4x-12)=7x-18
8x-24=7x-18
x=6
HOPE IT HELPS YOU '_'
1). 12 is the answer for number 1
Answer:
6
Step-by-step explanation:
Usually the missing number is 1. So, if the "y" is 1, then you multiply 6 and 1. You have 6.
Hope this helped, have a great day/night!