The figure shown is an equilateral triangle. Calculate the length of each side and give your answer in cm.

First side:2x-7

Second side:x+y-9

Third side:y+5

Given at you have an equilateral triangle, all sides have the same length.

Therefore,

First side 2x-7 = Second side x+y-9 = Third side y+5

Let us look at the second and third sides for now:

x+y-9 = y+5

x = y+5 - (y-9)

x = y-y+5+9

x = 14

Then we look at equating the first and third sides:

2x-7 = y+5

y = 2x-7-5

Substitute x = 14 in the equation above:

y = 2 (14) - 7-5

= 28-7-5

= 21-5

= 16

The length of the third side is:

y+5 = 16 + 5 = 21

Given that the length of each sides are the same in an equilateral triangle, all sides have the length 21cm.