15) Marissa is 3 years older than her younger brother. Her older brother is twice as old as her younger brother. Her older brother is 18. How old are Marissa and her younger brother?

Question

15)  Marissa is 3 years older than her younger brother. Her older brother is twice as old as her younger brother. Her older brother is 18. How old are Marissa and her younger brother?

Rina · Answer

Marissa is 12 which means the younger bro is 9

Sammyjoo · Answer

I know the answer, but is there a special formula to work it out.