Answer:
x...third number
4x...second number
x-9...first number
(x)+(4x)+(x-9)=141
x+4x+x-9=141
6x-9=141
Let's add 9 to both sides...
9+6x-9=141+9
6x=150
Let's divide both sides by 6...
(6x)/6=150/6
x=25
third number...25
second number...(4)(25)=100
first number...(25-9)=16
Let's check our work...
25+100+16=141
141=141