Question

three consecutive multiples of 3 have a sum of 84

Answer 1

let the three consecutive multiples of 3 is
x,x+3, ,x+6
atq
x+x+3+x+6=84
3x+9=84
x+3=28
x=25

Answer 2

let the three consecutive mutilpes are x, x+3,x+6
then x+x+3+x+6=84
3x+9=84
3x=75. x=25
now substitute x in reaming
then the numbers are 25,28,34