Question

Function,d(r) = 0.034r , is used to convert Russian rubles in United States dollars, and function, e(d) = 0.76d , is used to convert United States dollars into European euros. Use composition of functions to find the equivalent value of 2000 Russian rubles in European euros. Round the product of the decimal numbers in the composite function to the nearest thousandth.

Answer 1

We have two functions, one which converts rubles to USD and one which converts USD to euros. If we want to convert from rubles to euros, we could just convert it to USD and then euroes.

2000₽ ⇒ USD
$d(r)=0.034r\\d(2000)=0.034(2000)=68$

$68 USD ⇒ €
$e(d)=0.76d\\e(68)=0.76(68)=\boxed{51.68}$

Extra: If you wanted, you could create a function to convert rubles into euroes.
Just substitute that 0.034r for d in e(d) = 0.76d and...$e(r)=0.76(0.034r)=0.02584r$