Question 418733
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Let the longest side be x (we need to label it so we have somewhere to start).  Then the other sides are 8 less than x or just x-8 and half of x or 1/2 x
so we have 3 sides, x, 1/2 x and x-8.  The perimeter is the distance around the triangle or the sum of the 3 sides and we are told that it is 42 meters.
Therefore, {{{x+(1/2x)+(x-8)=42}}}
Combine your x and you get {{{2.5x-8=42}}}
Add 8 to both sides and you get 2.5x=50 and x=20 meters
then plug in x to find out the side lengths.