The property that allows you to write the equation −4y=−8 as the first step to solving the system of equations is (a) Substitution Property of Equality
The equations are given as:
[tex]x - 3y = 1[/tex]
[tex]x + y = 9[/tex]
Make x, the subject in the second equation
[tex]x = 9 - y[/tex]
Substitute 9 - y for x in the first equation
[tex]9 - y - 3y = 1[/tex]
Collect the like terms
[tex]-y -3y =1 - 9[/tex]
Evaluate the like terms
[tex]-4y =- 8[/tex]
Hence, the property is (a) Substitution Property of Equality
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