Answer:
x+4y is not change because it's parallel what changes is the result 8 + 4 × 2 = 16 so the equation is x + 4y = 16
So Maurice would have 2N nickels
Total number of coins is N + 2N + 9 = 3N + 9
Each nickel is 5 pennies
3N of nickels = 15N pennies
-----------
Their worth is 84 cents
15N + 9 = 84
15N = 75
N = 75/15 = 5
N = 5
This means Nina has 5 nickels.
I think that using the elimination method is the best, because it is the only method that I use when solving these types of equation. For example, for these two equations, you need to multiply one of the equations by a certain number so that you'd be able to find x and y. The elimination method is the method that tells you to do that. It is also the easiest method.
~Hope I helped!~
You can first take out an x^2 from each number , 3x^6 - 39x^4 + 108x^2 = x^2 ( 3x^4 - 39x^2 + 108) Then just factor and solve for the zero's of the equation
