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If 28x -5y=36and 15x+5y+18=68, whatis the value of x ? |
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Answer» 1 ` 28x-5y=26` `(+15 +5y=50)/({:(43x, ""=86),(x, ""=2 ):}` Choice (B) is correct. If you feel more comfortable USING substitution, you can maximize efficiency by solving one equation for 5y and substituting that VALUE into the other equation: `15x + 5y =50` `5y =50-15x` `28x -(50-15x ) =36` `43x -50 =36` `43x =86` `x =2` Note that the arithmetic is fundamentally the same, but the setup using combination is quicker and visually easier to follow. |
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