[Emergency] Revision Techniques

[Safira]

B. A pen costs 50p and a pencil costs 40p. Duncan has £6.50 to spread on pens and pencils.

Ok after a lengthy time I came up with an answer of 5x +10y ≤ 650 but the answer sheet says 5x+ 4y=65. It makes no sense how would they simplify to that.

I think this is correct. It takes the second part of the question into consideration rather than the first bit; any better mathematicians please correct me.

I do believe it goes like this:

≤ = less than or equal to.

x = Pens

y = Pencils

() = Price

Therefore,

Price of pens + Price of pencils ≤ £6.50.


The prices for the pens and pencils are in pence, so you need to convert the total amount (£6.50) into pence also - 650.

Now, if you fill in the gaps of X + Y, you would get:
50p x X + 40p x Y ≤ 650p.

The numbers you have are 50, 40, and 650.
Now for the really difficult and intense bit. Find the highest common factor. Or the easiest. It's 10.

So now you simplify the numbers into 5, 4, and 65. (Divide 50, 40 and 650 by 10)

And there's your answer:
5x + 4y ≤ 65

I had a look at what you did.

DO NOT, I REPEAT FOR THE LOVE OF PINGU, DO NOT TRY AND SOLVE THE QUESTION.

That's where you went wrong.

-Saf