Question
Solve for $x$ and $y$:
$0.4x + 0.3y = 1.7,$
$0.7x - 0.2y = 0.8$.
$0.4x + 0.3y = 1.7,$
$0.7x - 0.2y = 0.8$.
✓
Answer
The given equations are:
$0.4x + 0.3y = 1.7 ...(i)$
$0.7x - 0.2y = 0.8 ...(ii)$
Multiply $(i)$ by $0.2$ and $(ii)$ by $0.3$ add them
$\Rightarrow 0.8x + 2.1x = 3.4 + 2.4$
$\Rightarrow 2.9x = 5.8$
$\Rightarrow x = 2$
Substitute $x = 2$ in $(i)$, we get
$\Rightarrow 0.4(2) + 0.3y = 1.7$
$\Rightarrow y = 3$
So, $x = 2$ and $y = 3$.
$0.4x + 0.3y = 1.7 ...(i)$
$0.7x - 0.2y = 0.8 ...(ii)$
Multiply $(i)$ by $0.2$ and $(ii)$ by $0.3$ add them
$\Rightarrow 0.8x + 2.1x = 3.4 + 2.4$
$\Rightarrow 2.9x = 5.8$
$\Rightarrow x = 2$
Substitute $x = 2$ in $(i)$, we get
$\Rightarrow 0.4(2) + 0.3y = 1.7$
$\Rightarrow y = 3$
So, $x = 2$ and $y = 3$.
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