alleryIf $2x + y = 23$ and $4x - y = 19$, what is the value of $(5y - 2x)$?
A31
B37
C43
D49
Answer & Solution
Correct answer: A. 31
1. Adding both equations: $(2x + y) + (4x - y) = 23 + 19 \Rightarrow 6x = 42 \Rightarrow x = 7$.
2. Substituting $x = 7$ into the first equation: $2(7) + y = 23 \Rightarrow 14 + y = 23 \Rightarrow y = 9$.
3. Now evaluate $5y - 2x = 5(9) - 2(7) = 45 - 14 = 31$.
_Source: NCERT Class 10 Mathematics, Ch3 'Pair of Linear Equations in Two Variables'_
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