Problem:
Soo is 8 years older than Marco. In four years, Soo will be twice as old as Marco. How old is Soo now?
#### Step-by-Step Solution:
1.
Understand the Question and Any Restrictions:
- Soo is currently 8 years older than Marco.
- In four years, Soo's age will be twice Marco's age at that time.
- We need to find Soo's current age.
2.
Assign Variables:
- Let \( M \) represent Marco's current age.
- Since Soo is 8 years older than Marco, Soo's current age is \( M + 8 \).
3.
Create an Equation:
- In four years:
- Marco's age will be \( M + 4 \).
- Soo's age will be \( (M + 8) + 4 = M + 12 \).
- According to the problem, in four years, Soo's age will be twice Marco's age:
\[
M + 12 = 2(M + 4)
\]
4.
Solve the Equation:
- Expand the right-hand side:
\[
M + 12 = 2M + 8
\]
- Rearrange the equation to isolate \( M \):
\[
12 - 8 = 2M - M
\]
\[
4 = M
\]
- So, Marco's current age is \( M = 4 \).
5.
Find Soo's Current Age:
- Since Soo is 8 years older than Marco:
\[
\text{Soo's current age} = M + 8 = 4 + 8 = 12
\]
6.
Verify the Solution:
- Marco's current age is 4.
- Soo's current age is 12.
- In four years:
- Marco's age will be \( 4 + 4 = 8 \).
- Soo's age will be \( 12 + 4 = 16 \).
- Check if Soo's age is twice Marco's age in four years:
\[
16 = 2 \times 8
\]
This is true, so the solution is correct.
Final Answer:
\[
\boxed{C}
\]
Parent Tip: Review the logic above to help your child master the concept of gmat practice worksheet.
