document.write( "Question 1144508: I am trying to help my son with this but am lost there are no videos to help me that I can find his problem is...\r
\n" ); document.write( "\n" ); document.write( "3a-b-5c=22
\n" ); document.write( "4c=-12-a-2b
\n" ); document.write( "2a-19=6b+3c \n" ); document.write( "

Algebra.Com's Answer #765656 by MathTherapy(10552) $\"\"$ $\"About$

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\n" ); document.write( "I am trying to help my son with this but am lost there are no videos to help me that I can find his problem is...\r
\n" ); document.write( "\n" ); document.write( "3a-b-5c=22
\n" ); document.write( "4c=-12-a-2b
\n" ); document.write( "2a-19=6b+3c
\n" ); document.write( "

There are many methods that can be used to solve for the variables. One is to SOLVE one of the equations for one of the variables. I chose to solve eq (ii) for \"a\"
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document.write( "3a - b - 5c = 22 ------ eq (i)
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document.write( "4c = - 12 - a - 2b______a = - 2b - 4c - 12 ------- eq (ii)
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document.write( "2a - 6b - 3c = 19 ------ eq (iii)\r
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document.write( "3(- 2b - 4c - 12) - b - 5c = 22 ------ Substituting - 2b - 4c - 12 for a in eq (i)
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document.write( "- 6b - 12c - 36 - b - 5c = 22
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document.write( "- 7b - 17c = 58 ------ eq (iv)
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document.write( "2(- 2b - 4c - 12) - 6b - 3c = 19 ------ Substituting - 2b - 4c - 12 for a in eq (iii)
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document.write( "- 4b - 8c - 24 - 6b - 3c = 19
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document.write( "- 10b - 11c = 43 ------ eq (v)
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document.write( "  70b + 170c = - 580 ---- Multiplying eq (iv) by - 10 ----- eq (vi)
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document.write( " - 70b - 77c = 301 ------ Multiplying eq (v) by 7 --------- eq (vii)
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document.write( "         93c = - 279 ---- Adding eqs (vii) & (vi)
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document.write( "          \r
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document.write( "- 10b - 11(- 3) = 43 ------ Substituting - 3 for c in eq (v)
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document.write( "- 10b + 33 = 43
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document.write( "- 10b = 43 - 33
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document.write( "- 10b = 10
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document.write( "   \r
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document.write( " a = - 2(- 1) - 4(- 3) - 12 ------ Substituting - 3 and 1 for c and b, respectively, in eq (ii)
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document.write( " a = 2 + 12 - 12
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