Answer:
a) 61
The friend's ages are consecutive, therefore they are each one year apart. There are 3 friends whose ages add up to 180 in total.
[tex]180 / 3 = 60[/tex]
In order to make three consecutive numbers, subtract one and add one to 60.
[tex]60 - 1 = 59\\60 + 1 = 61[/tex]
You get 59, 60, and 61.
61 is the oldest age, that's your answer.