The expression that represents the perimeter in centimetre of the triangle is 4r - 16s + 4t
Perimeter of a triangle is the sum of the whole sides. The triangle has three sides. Therefore, the perimeter is the sum of the three sides.
The side length are as follows;
Therefore,
perimeter = r - 10s + 3r + 2t + 2t - 6s
combine like terms
perimeter = r + 3r - 10s - 6s + 2t + 2t
perimeter = 4r - 16s + 4t
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