Given :
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To Find :
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Solution :
We know that,
[tex]\qquad{ \bold{ \pmb{2(Length + Breadth ) = Perimeter_{(rectangle)}}}}[/tex]
Let's assume the width of the rectangle as x inches. Then the length will become (3x + 9).
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Now, Substituting the given values in the formula :
[tex]\qquad \dashrightarrow{ \sf{2(3x + 9 + x )= 138}}[/tex]
[tex]\qquad \dashrightarrow{ \sf{2(4x + 9 )= 138}}[/tex]
[tex]\qquad \dashrightarrow{ \sf{8x + 18= 138}}[/tex]
[tex]\qquad \dashrightarrow{ \sf{8x = 138 - 18}}[/tex]
[tex]\qquad \dashrightarrow{ \sf{8x = 120}}[/tex]
[tex]\qquad \dashrightarrow{ \sf{x = \dfrac{120}{8} }}[/tex]
[tex]\qquad \dashrightarrow{ \bf \: x = 15}[/tex]
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Therefore,
[tex]\qquad { \pmb{ \bf{ Width _{(frame)} = x = 15 \: inches}}}\:[/tex]
[tex]\qquad { \pmb{ \bf{ Length _{(frame)} = (3x + 9) \: = 3(15) + 9 = 54 \: inches}}}\:[/tex]