Answer:
10, 19 and 57
Step-by-step explanation:
let the first number be a, the second be b and the third be c
a+b+c=86
the second number is 9 less than the first
a=b+9------i
b=a-9
the third number is 3 times the first
c=3a------ii
a=c/3
therefore
b+9=c/3
c=3(b+9)
b+9+b+3(b+9)=86
b+9+b+3b+27=86
collecting like terms
5b=86-(27+9)
5b=86-36
5b=50
therefore
b=10
recall i to solve for a
a=b+9
a=10+9
a=19
recall ii to solve for c
c=3a
c=3*19
c=57
