When I was 4 my sister was twice my age .Now am 20.How old is my working.Explain and show working

$$\textbf{Step 1:}$$ When you were 4 years old, your sister was twice your age. $$\text{You:} \quad 4 \text{ years old}$$ $$\text{Sister:} \quad 2 \times 4 = 8 \text{ years old (twice your age)}$$ This means there's a 4-year age difference between you and your sister. $$\textbf{Step 2:}$$ Now, you are 20 years old. $$\text{You:} \quad 20 \text{ years old}$$ Since the age difference between you and your sister is always 4 years, your sister's current age can be found by subtracting the age difference from your current age. $$\text{Sister's current age} = \text{Your age - Age difference} = 20 - 4 = 16 \text{ years old}$$ So, your sister is currently 16 years old.