Please help....

1. When Mrs Lee was 40 years old, her son was twice her daughter's age. Mrs Lee will be twice her son's age when her daughter is 28 years old. How old was Mrs Lee when her daughter was 30 years old?

2. Mrs Singh is now 5 times as old as her son. 5 years ago, she is 15 times as old as her son. How old is Mrs Singh now?

Thks

Concept: Constant Difference + Model Drawing

Question 2 : Constant difference

For your first question, you can find it and similar questions here Constant Difference

Thks Chris.

Hi
Thks for the solution.
Pls enlighten, how do we get 3u is 40-28?
If her son's age is twice her daughter's age, so when her daughter is 28, her son is not 56?

While not answering your question directly, maybe looking through this flash file help you to understand the steps involved.

Note: You can click the button shown in the red circle at the top right corner, to make the slide show appear in full screen mode.

Miki Theseira wrote:
Hi
Thks for the solution.
Pls enlighten, how do we get 3u is 40-28?
If her son's age is twice her daughter's age, so when her daughter is 28, her son is not 56?

Referring back to the model for Case 1
Notice that 3u + 28 --> 40
So 3u --> 40 - 28


Her son is only twice her daughter's age when Mrs Lee is 40 years old. When her daughter is 28 her son will not be twice as old anymore. Let's use real numbers to illustrate.

When Mrs Lee was 40 years old, her son was 8 years old, so he is twice as old as the daughter who is 4 years old.
When her daughter is 28 years old (which is 28 - 4 = 24 years later), her son should be 8 + 24 = 32 years old. 32 is not twice as old as 28.