The first side of a triangle is 9 m shorter than the second side. The third side is 3 times as long as the first side. The perimeter is 39 m. What is the length of the longest side?

Longest side is 18 m

Step-by-step explanation:

1st side : x - 9

3rd : 3 (x-9)

If perimeter is 39, then, x + (x-9) + 3 (x-9) = 39

5x - 36 = 39

5x = 75

x = 15

Therefore,

1st side = 6

2nd side = 15

3rd side = 18

The length of the longest side is 18 m.

Step-by-step explanation:

Let x = length of the second side.

Then the length of the first side is x - 9.

The length of the third side is 3 (x - 9).

Add the three lengths and set equal to the perimeter.

x + x - 9 + 3 (x - 9) = 39

2x - 9 + 3x - 27 = 39

5x - 36 = 39

5x = 75

x = 15 (second side)

x - 9 = 15 - 9 = 6 (first side)

3 (x - 9) = 3 (15 - 9) = 3 (6) = 18 (third side)