Lana is the oldest of four sisters. Her youngest sister is half her age. The other two sisters are twins 2 years younger than Lana. When the four sisters' ages are added together, the result is 45. If the youngest sister is n years old, what is n? will give meadel

If Lana's age is L, her youngest sister is L/2 (or 0.5L) and the twins L-2. Add all these together (remember that there are two sisters who are L-2 years old):

0.5L + L-2 + L-2 + L = 45

Simplify the L's by adding them all together, we get:

3.5L - 2 - 2 = 45

3.5L - 4 = 45

Now add 4 to both sides:

3.5L = 49

Now divide both sides by 3.5

L = 49/3.5 = 14. Now we know that Laura is 14, so her youngest sister must be 7.