So with this you will be using proportions, and this proportion is gonna be 
Firstly, you want to cross-multiply to get 
Next, just divide each side by 4, then your answer will be 
Answer:
These are two equilateral triangles and all the sides of an equilateral triangle are equal. The question even says so so that's the answer, all the sides of the equilateral triangles are equal so all the sides equate to each other
1) This probability is given by
... C(40,5)·0.12⁵·0.88³⁵ ≈ 0.18665 . . . . . where C(n, k) = n!/(k!(n-k)!)
2) This probability is given by
... 0.88⁴⁰ ≈ 0.00602
3) This is the complement of the probability that all have failed.
... 1 - 0.12⁴⁰ ≈ 1.0000