I tryed my best to figure out what all of the numbers were. if i got any wrong then please tell me and i will put the right answer in the comments.
1) 3/5= 5/x   (cross multiply)
     3x=5(5)
     3x=25
       x= 25/3 -or- 8.33
2) 2/4=x/12<span>   (cross multiply</span><span>)
</span> 2(12)=4x
     24=4x
       6=x
3) 10/x=5/9<span>   (cross multiply</span><span>)
   10(9)=5x
       90=5x
       18=x
4) 5/5=x/18</span><span>   (cross multiply</span><span>)
 5(18)=18x
     90=18x
       5=x</span>
        
             
        
        
        
The amount of balls in a given layer can be found by squaring the layer it is in
4 layers
top layer (1st) is 1
2nd is 4
3rd layer is 9
4th is 16
add them up
1+4+9+16=30
30 in that pyramid
        
             
        
        
        
Answer:
6X8=48 10 more is 58 
Step-by-step explanation:
 
        
             
        
        
        
Answer:
(x-3) years
Step-by-step explanation:
We are given that 
Age of Jonathan= x years
Sage is 7 years older than Jonathan
It means 
Age of Sage=(x+7) years
We have to find the age of Sage 10 years ago.
10 Years ago,
Age of Jonathan=(x-10) years
Age of Sage=(x+7-10) years
Age of Sage=(x-3) years
Hence, 10 years ago, age of Sage =(x-3) years
 
        
             
        
        
        
So if brother was 10, 5 years ago, then 10+5=15, bro is 15 now
in 15 years, he will be 15+15=30 years old