Answer:
Maria is a fan of cookie packages, so she has made the calculations and discovered that 4 packages of cookies plus 5 dollars are equivalent to the price of 12 packages of cookies minus 11 dollars.
represents the price of a package of cookies,
so we have the 4 packages of cookies plus 5 dollars on one side of the equation

and on the other side of the equation the 12 packages of cookies minus 11 dollars

and if both sides are equivalent we get:
