Answer:
a scalene triangle
Step-by-step explanation:
all angles are different lengths
Step-by-step explanation:
Equation: 
First step:

Second step:

Third step:

Fourth step:

Certain means the event will happen.
Impossible means the event would never happen.
It will take him 16 hours because 25 is 1/4 of 100% so 4 times 4 is 16. So 16 is your answer :)
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