Question 158850
3 numbers:
a
a+1
a+2

words to symbols:
a(a+1)-3(a+2)=57
a^2+a-3a-6=57
a^2-2a-63=0
(a+7)(a-9)=0
so a=-7 or a=9. We want a to exist in the set of integers. Thus, we exclude a=-7 as a solution.

The numbers, then, are 9, 10, 11.

Check:
9(10)-3(11)=90-33=57

yes