I'm really confused. explain step by step .

Hello!

We know that any number multiplied by zero is ALWAYS equal to zero. In this question, we can use that to our advantage.

In my opinion, but biggest here is the get rid of the constant term 5. So, we can make the x-term is equal to 5 because 5 subtract 5 is equal to zero (if you ignore the term in the middle).

Since we assigned 5 to the variable x, we substitute 5 into the given expression and we get: 5 + 4(5)(5 - y) - 5, which is equal to 20(5 - y). If we take the term 5 - y, we can determine that if we substitute y for 5, it will make it equal to zero: 5 - (5) = 0. Also, since the term 4x is being multiplied to (5 - y), it will be equal to zero because 20 × 0 = 0 (after we substitute y = 5 into the expression).

Since we said that x and y are equal to 5, we can check it to make sure.

5 + 4(5)(5 - 5) - 5

5 + 4(5)(0) - 5

5 + 20(0) - 5

0 + 0 = 0 | The expression is equal to zero!

Therefore, the values of x and y are equal to 5.

a is the correct