Answer:
3 , 6 , 9
Step-by-step explanation:
suppose these three numbers are a, b, and c. we can write the following equations:
#1 a+b+c = 18
#2 a+b = 15
#3 a = 3c
if we subtract #2 from #1 we have c = 3. From #3 we have a = 3(3) = 9. Finally, since a+b+c = 18 we plug in our known values for a and c to obtain b = 6. therefore our three numbers are a = 9, b = 6, c = 3.
