Question 121339
Solve 5x + 4y = 12 for y What does 12 for y mean? 
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You read that wrong.  It should be read like this:

Solve this equation for the variable y:

5x + 4y = 12
                    Get the y-term by itself on the left by
                    adding -5x to both sides:

     4y = -5x + 12
                    Divide every number by the coefficient of y,
                    which is 4:

     {{{(4)/4}}}y = {{{(-5)/4}}}x + {{{12/4}}}

                y = {{{(-5)/4}}}x + 3

                y = {{{-5/4}}}x + 3
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What is the slope and y intercept of this line? 
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Rule:

For the equation of line

               y = mx + b

the slope = m and the y-intercept is the point (0,b)

Compare

                y = {{{-5/4}}}x + 3

with            y = mx + b

and you see that m = {{{-5/4}}} and b = 3

so the slope = m = {{{-5/4}}} and the

y-intercept = (0,b) = (0,3) 

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What is the corresponding value of y when x=16.

Substitute 16 for x in

                y = {{{-5/4}}}x + 3

                y = {{{-5/4}}}(16) + 3

                y = -20 + 3

                y = -17

Edwin</pre></font></b>