Algebra 2 Common Core

Published by Prentice Hall
ISBN 10: 0133186024
ISBN 13: 978-0-13318-602-4

Chapter 3 - Linear Systems - 3-2 Solving Systems Algebraically - Practice and Problem-Solving Exercises - Page 148: 70

Answer

Georgia has two more dimes than quarters in her bag.

Work Step by Step

Let us define some variables to set up the equations to be solved: $x$ = the number of dimes Georgia has $y$ = the number of quarters Georgia has Each dime is worth $10$ cents and each quarter is worth $25$ cents, so $0.10x$ = the amount of money Georgia has in dimes $0.25y$ = the amount of money Georgia has in quarters Let us set up an equation that states the number of dimes and quarters Georgia has is equal to $18$: $x + y = 18$ We set up another equation that states that the amount of money Georgia has in dimes and the amount of money she has in quarters equals three dollars: $0.10x + 0.25y = 3$ Let us put the two equations together to form the system: $x + y = 18$ $0.10x + 0.25y = 3$ Let us try to solve using substitution. We solve the first equation for $x$ in terms of $y$ by subtracting $y$ from both sides of the equation to isolate $x$: $x = 18 - y$ Let us plug this expression for $x$ into the second equation to solve for $y$: $0.10(18 - y) + 0.25y = 3$ Use distributive property to simplify: $0.10(18) - 0.10y + 0.25 y = 3$ $1.8 - 0.10y + 0.25y = 3$ Combine like terms: $1.8 + 0.15y = 3$ Subtract $1.8$ from each side to isolate constants to the right side of the equation: $0.15y = 1.2$ Divide each side by $0.15$ to solve for $y$: $y = 8$ Now that we have the value for $y$, we can use this value to substitute for $y$ in the first equation: $x + 8 = 18$ Subtract $8$ from both sides of the equation to solve for $x$ $x = 10$ Thus, Georgia has $10$ dimes and $8$ quarters. This means that Georgia has two more dimes than quarters in her bag.
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