Hello!
Answer:

Explanation:
→ Let my age be x.
→ We have this equation:

→ Let's solve x in this equation to find my age:
◼ Subtract 300 from both sides:

◼ Simplify both sides:

◼ Divide both sides by -3:

◼ Simplify both sides:

Conclusion:
If 300 reduced by 3 times my age is equal to 72, my age is 76.