A 50 cm length of ribbon costs x dollars. Find an expression for the cost of y meters of ribbon. Give your answer to its simplest form.

My solution:

Let y = the total cost for a certain amount of x ribbons

Let x = the cost per ribbon

I write a linear equation to express a relation between x, y and 50.

I say the equation is y = 50x.

Is this correct? If not, why not?