Create an equation

Stephanie adds pennies, nickels, and quarters to a scale until the mass of the combined coins is 75 grams.  Each penny has a mass of 2.5 grams, each nickel has a mass of 5 grams, and each quarter has a mass of 5.7 grams.

Create an equation to model this situation, where x is the number of pennies, y is the number of nickels, and z is the number of quarters that Stephanie can put on the scale so that the mass of the combined coins is exactly 75 grams.

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x = number of pennies
y = number of nickels
z = number of quarters

2.5x + 5y + 5.7z = 75   {mass of each coin times number of coins equals total mass}

Ask Algebra House

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