Question 1052410
"perimeter of a triangle is 19 cm"
{{{A+B+C=19}}}
.
.
"longest side is twice that of the shortest side"
{{{C=2A}}}
.
.
"longest side is 3cm less than the sum of the lengths of the other two sides,
{{{C=(A+B)-3}}}
{{{A+B=C+3}}}
Substitute into the first equation,
{{{(C+3)+C=19}}}
{{{2C=16}}}
{{{C=8}}} {{{cm}}}
So then from the second,
{{{8=2A}}}
{{{A=4}}}{{{cm}}}
and from the first,
{{{4+B+8=19}}}
{{{B=7}}}{{{cm}}}