5x-y=7
-y=-5x+7
y=5x-7
f(x)=5x-7
Yes the two goods are therefore substitutes <span>if the price f a good X rises, causing the demand for good Y to fall for example two substitutes tea and coffee and the price of tea will be increase when the demand of coffee will decrease because now more people will demand tea and when demand increases price increases.
Hope it helps.
</span>
