Question 224933
{{{y=4x}}}  Equation 1
{{{y=-x-15}}} Equation 2


Step 1.  Substitute y=4x of Equation 1 into Equation 2.


{{{4x=-x-15}}}


Step 2.  Add x to both sides of the equation


{{{4x+x=-x+15+x}}}


{{{5x=15}}}


Step 3.  Divide 5 to both sides of the equation


{{{5x/5=15/5}}}


{{{x=3}}}


Step 4. ANSWER:  Solution is {{{x=3}}}


I hope the above steps were helpful. 


For free Step-By-Step Videos on Introduction to Algebra, please visit http://www.FreedomUniversity.TV/courses/IntroAlgebra or for Trigonometry visit http://www.FreedomUniversity.TV/courses/Trigonometry.


And good luck in your studies!


Respectfully,
Dr J


http://www.FreedomUniversity.TV
http://www.Facebook.com/FreedomUniversityTV
http://www.Twitter.com/FreedomUTV