Singaporean Math problems 2

Johnx

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Raju had p stamps. 120 of his stamps were local stamps and the rest were foreign stamps. Raju's friend then gave him 2p foreign stamps.

a) How many foreign stamps did Raju have at first?

my answer: 2p + p = 120. So he had 40 foreign stamps.
b) Raju had 165 stamps at first. How many foreign stamps did he have in the end?

my answer: 2p + p = 165. So he had 65 foreign stamps.


Thank you to anyone who can answer these questions.
 
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Raju had p stamps. 120 of his stamps were local stamps and the rest were foreign stamps. Raju's friend then gave him 2p foreign stamps.

a) How many foreign stamps did Raju have at first?

my answer: 2p + p = 120. So he had 40 foreign stamps.

Why would you add the total number of stamps he started with, and the number of foreign stamps added, and get the number of local (non-foreign) stamps he has? That makes no sense.

Instead, just look at the initial situation. He has p stamps, of which 120 are local and the rest are foreign. You're being ask how many "the rest" is (as an expression).

b) Raju had 165 stamps at first. How many foreign stamps did he have in the end?

my answer: 2p + p = 165. So he had 65 foreign stamps.

You are being told that p = 165, right? That's not the same as changing your 120 to 165.

Use the correct answer to part (a) to find how many foreign stamps he started with; then add in the foreign stamps he was given.
 
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