Answer:
30 years old
Step-by-step explanation:
Joe's age can be set to x. Since Billy is twice as old as Joe, his age can be set to 2x. They add up to 45. You can set up an equation, 2x+x=45.
Simplify the equation.
3x=45, x=15
Joe is 15. Billy is 2(15)=30.
