Question 318753
1.{{{2W + 2L = 38}}}
I switched to capital letters since the small L and the number 1 look similar.
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"one side is 11cm longer yhan the other side"
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Pick one to be longer, it doesn't matter which one you choose.
2.{{{L=W+11}}}
Those are your two equations.
Substitute eq. 2 into eq. 1,
{{{2W+2(W+11)=38}}}
{{{2W+2W+22=38}}}
{{{4W+22=38}}}
{{{4W=16}}}
{{{highlight(W=4)}}}
Then from eq. 2,
{{{L=W+11}}}
{{{L=4+11}}}
{{{highlight(L=15)}}}