Question

On a recent day, 8 euros were worth $11 and 24 euros were worth $33. Enter an equation of the form y = kx to show the relationship between the number of euros and the value in dollars. Let y be the value in dollars and x be the number of euros.

Answer 1

Put the numbers in the given equation and solve for k.

... $11 = k·(8 €)

Divide by the coefficient of k:

... k = $11/(8 €) = 1.375 $/€

Then your equation is ...

... y = (1.375 $/€)x

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It is fairly common to leave the units out of such equations, assuming that everyone understands that x is in euros and y is in dollars and the conversion factor includes a unit change from euros to dollars. Thus, you might expect to see ...

... y = 1.375·x