Multiply (x+y) (y-4)

xy - 4x + y^2 - 4y

Step-by-step explanation:

Try to take each step slowly so that you don't get lost or miss anything and remember to read from left to right:

(x + y) (y - 4)

Begin with multiplying x to y and - 4:

xy - 4x + y (y - 4)

Then multiply y with y and - 4:

xy - 4x + y^2 - 4y