Question 1094582
<br>The algebra you need to do is nearly always easier if you can set up the problem using only one variable instead of 3.<br>
Since the given information says the shortest side is one-third the longest side, to avoid fractions I would let x be the length of the shortest side, making the length of the longest side 3x.  Then from the given information we can determine that the length of the third side is 3x-7.<br>
So the three side lengths are x, 3x, and 3x-7; and the perimeter is 70:
{{{x + 3x + 3x-7 = 70}}}
{{{7x-7 = 70}}}
{{{7x = 77}}}
{{{x = 11}}}<br>
The shortest side is 11; that makes the longest side 3*11 = 33 and the longest side 33-7 = 26.