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
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Their worth is 84 cents
15N + 9 = 84
15N = 75
N = 75/15 = 5
N = 5
This means Nina has 5 nickels.
This is not the best question I've ever seen. The wording is the problem, and it's not your fault. The melting point of Krypton is about - 160 oC. It means that numerically the melting point of Krypton is 4 times lower than that of mercury.
Krypton = 4*M
M = - 39
Krypton = 4*-39
Krypton = - 156o C
Now you want to make it something like K(1/4) = - 39 which would be fine. You can't use - 1/4. If you do, your answer will come out to be + 156 which is not what you mean. If this was a multiple choice question, your answer would be the second best one.
The graphs are similar because they both have miles per hour and the graphs are differnt because Flavia and Jenya have different speed