U know I can replace ur x and you won’t even know y boom
        
             
        
        
        
Answer:
no, i cant solve it in paper but i can in my brain
Step-by-step explanation:
 
        
             
        
        
        
There are 5 pennies in a nickel, and 10 pennies in a dime.  Now in $3.90 there are 390 pennies.
n = number of nickels in the pile
d = number of dimes in the pile
we know the pile has 55 coins, therefore whatever "n" and "d" are, we know that 
n + d = 55.
now, "n" is how many nickel coins are there, how many pennies is it in total?  well, 5 pennies to a nickel, for "n" nickels, will then be 5(n) or 
5n.
and "d" is how many dime coins are there, so therefore in "d" coins, there are 10(d) pennies, or 
10d.
we also know the total amount of pennies is 390, therefore 
5n + 10d = 390.

how many nickel coins are there anyway?  well, n = 55 - d.
 
        
        
        
C) it changed 0 feet
The overall change would be 0; first it would be up 750, but then coming back down 750 effectively cancels that change.