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If $8 x-9 y=20$ and $7 x-10 y=9$, then what is $2 x-y$ equal to?
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Verified Answer
The correct answer is:
10
$8 x-9 y=20$ or $80 x-90 y=200$...(1)
$7 x-10 y=9$ or $63 x-90 y=81$...(2)
Subtracting $(2)$ from $(1)$, we get $17 \mathrm{x}=119$
$\mathrm{x}=7$
$8 \times 7-9 y=20$
$9 y=36$
$y=4$
$2 x-y=2 \times 7-4=10$
$7 x-10 y=9$ or $63 x-90 y=81$...(2)
Subtracting $(2)$ from $(1)$, we get $17 \mathrm{x}=119$
$\mathrm{x}=7$
$8 \times 7-9 y=20$
$9 y=36$
$y=4$
$2 x-y=2 \times 7-4=10$
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