First, we have to figure out the expression for the total price of potatoes. We find that by multiplying the price of potatoes per pound by how many pounds were bought. Robert bought x pounds of potatoes at $1.99 per pound. This can be written as:
$1.99x
Next, we have to find the equation for Robert's change. Change is defined as amount paid minus cost. In this scenario, Robert paid $10, and we already know the cost is $1.99x. So using this information, we can now write the equation:
$10 - $1.99x
So the answer is a.
