<PRE><B>Question 568</B>
your first question has the same line, so we will solve your second. 

since you have two variables (two unknowns - x and y), they are giving you two equations so that you can solve for each variable by substitution.
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step 1: write equations in linear format &lt;b&gt;y = mx + b&lt;/b&gt;
so for &lt;i&gt;3x + 4y = 12&lt;/i&gt;, we write it as &lt;i&gt;4y = -3x + 12&lt;/i&gt;. 
for &lt;i&gt;6x + 14y = 30&lt;/i&gt;, we write it as &lt;i&gt;14y = -6x + 30&lt;/i&gt;
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step 2: simplify your equations.
for the equation &lt;i&gt;4y = -3x + 12&lt;/i&gt;, divide the whole equation by &lt;b&gt;4&lt;/b&gt; so that the coefficient of y will equal 1. 
&lt;i&gt;4y/4 = -3x/4 + 12/4&lt;/i&gt;
after dividing, this will be written as &lt;i&gt;y = -3x/4 + 3&lt;/i&gt;
2nd equation: &lt;i&gt;14y = -6x + 30&lt;/i&gt; will be divided by &lt;b&gt;14&lt;/b&gt; and will be rewritten as &lt;i&gt;y = -3x/7 + 15/7&lt;/i&gt;
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step 3: substitute y in the first equation since there are two variables. 
since y = -3x/7 + 15/7, when we combine your 2nd equation with your 1st, we write it as &lt;i&gt;-3x/7 + 15/7 = -3x/4 + 3&lt;/i&gt;.
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step 4: bring x&#39;s to one side of the equation and your constants to one side.
&lt;i&gt;-3x/7 + 3x/4 = 3 - 15/7&lt;/i&gt;
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step 5: find the lowest common denominator to get rid of the fractions. thus, we will multiply the whole equation of -3x/7 + 3x/4 = 3 - 15/7 by &lt;b&gt;28&lt;/b&gt; and get:
&lt;i&gt;-12x + 21x = 3(28) - 60
9x = 84 - 60
9x = 24
x = 24/9 = &lt;b&gt;8/3&lt;/b&gt;&lt;/i&gt;
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step 6: subsitute x into your original equation. we will use the 1st one &lt;i&gt;3x + 4y = 12
3(8/3) + 4y = 12
(the 3&#39;s cancel)
8 + 4y = 12
4y = 12 - 8
4y = 4
&lt;b&gt;y = 1&lt;/b&gt;&lt;/i&gt;
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Thus, &lt;font color=red&gt;x = 8/3 and y = 1&lt;/font&gt;
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