document.write( "Question 638983: I need help with substitution.\r
\n" ); document.write( "\n" ); document.write( "x+3=y\r
\n" ); document.write( "\n" ); document.write( "3x+4y=7\r
\n" ); document.write( "\n" ); document.write( "with steps & answers please and thank you \n" ); document.write( "

Algebra.Com's Answer #402588 by ankor@dixie-net.com(22740) $\"\"$ $\"About$

You can put this solution on YOUR website!
substitution.
\n" ); document.write( "x + 3 = y
\n" ); document.write( "3x + 4y = 7
\n" ); document.write( ":
\n" ); document.write( "From the 1st equation we know that: y = (x+3)
\n" ); document.write( "Substitute (x+3) for y in the 2nd equation
\n" ); document.write( "3x + 4(x+3) = 7
\n" ); document.write( ":
\n" ); document.write( "multiply what's inside the brackets
\n" ); document.write( "3x + 4x + 12 = 7
\n" ); document.write( ":
\n" ); document.write( "Add the x's, subtract 12 from both sides
\n" ); document.write( "7x = 7 - 12
\n" ); document.write( "7x = -5
\n" ); document.write( "x = $\"-5%2F7\"$
\n" ); document.write( ":
\n" ); document.write( "Find y
\n" ); document.write( "y = x + 3
\n" ); document.write( "substitute $\"-5%2F7\"$ for x
\n" ); document.write( "y = $\"-5%2F7\"$ + 3
\n" ); document.write( "Change 3 to 7ths
\n" ); document.write( "y = $\"-5%2F7\"$ + $\"21%2F7\"$
\n" ); document.write( "y = $\"16%2F7\"$
\n" ); document.write( ":
\n" ); document.write( "Solution: x = $\"-5%2F7\"$ ; y = $\"16%2F7\"$
\n" ); document.write( ":
\n" ); document.write( ":
\n" ); document.write( "Check solution in the 2nd equation
\n" ); document.write( "3x + 4y = 7
\n" ); document.write( "Replace x and y
\n" ); document.write( "3( $\"-5%2F7\"$ ) + 4( $\"16%2F7\"$ ) = 7
\n" ); document.write( " $\"-15%2F7\"$ + $\"64%2F7\"$ = 7
\n" ); document.write( " $\"49%2F7\"$ = 7
\n" ); document.write( "7 = 7; confirms our solutions,
\n" ); document.write( ":
\n" ); document.write( "Was this step-by-step enough for you to understand? C \n" ); document.write( "

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