Hello Tessarina Originally Posted by

**Tessarina** I'm really sorry to ask again,

but i was wondering whether you could also show me the whole working out for part b?

thank you

The total revenue is the number of items sold multiplied by the selling price per item. If we translate this into symbols, this is:

$\displaystyle R = nx$ ...(1)

because

$\displaystyle R =$ total revenue

$\displaystyle n =$ number of chairs sold

$\displaystyle x =$ selling price of one chair

But we showed in part (a) that:

$\displaystyle n = 550 - 5x$

So in equation (1), we can replace $\displaystyle n$ by $\displaystyle (550 - 5x)$ to get:

$\displaystyle R = (550-5x)x$

and, if we remove the brackets:

$\displaystyle R = 550x-5x^2$

OK now?

Grandad