Adding the parts in the ratio gives 18 so there are two triangles possible with perimeters less than 54cm where the side lengths are all integers: a 5, 6, 7 triangle or a 10, 12, 14 triangle.
Therefore the length of the longest side must be either 7cm or 14cm (unless you want to include non-integer side lengths, then it could also be 3.5cm, 1.75cm etc)
<span><span><span>9/10 - 7/20=(9x20) - (7x10)= 10x20= 110/200 110 divided by 10/ 200 divided by 10= 11/20. So that brings you to your answer of 11/20. hope this helps :)
