Answer:

Step-by-step explanation:
A ratio is a comparison of two quantities and can be written in several forms including fractions. It is most commonly written in fraction form or a:b. 
To write a ratio, we count the number of each quantity we are comparing or use the variable for that quantity. We write radius:circumference. Recall, the circumference of a circle can be found using  or
 or  .
.
We write r:  or r:
  or r: .
.
We can also write in fraction form:
 or
 or 
 
        
             
        
        
        
Answer:
156
Step-by-step explanation:
13 x 12 = 156
 
        
             
        
        
        
Simply multiply the baby's original weight, which is 7.25 lbs, by 2.5
7.25lbs x 2.5 = 18.125 lbs
The baby weighted 18.125 pounds at the end of 8 months.
Hope this helps and May the Force Be With You!
-Jabba
        
                    
             
        
        
        
let's recall that i⁴ = 1 so then    