Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

I can write cow in 13 letters.

Can You?

What do you see in the given picture?

Which Burger Is Different in below image?

Take one out and scratch my head, I am now black but once was red. What am I?

How can you take 2 from 5 and leave 4?

When can we add 2 to 11 and get 1 as the correct answer?

Two old friends, Jack and Bill, meet after a long time.

Three kids
Jack: Hey, how are you, man?
Bill: Not bad, got married and I have three kids now.
Jack: That's awesome. How old are they?
Bill: The product of their ages is 72 and the sum of their ages is the same as your birth date.
Jack: Cool..But I still don't know.
Bill: My eldest kid just started taking piano lessons.
Jack: Oh, now I get it.

How old are Bill's kids?

It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

I am a type of food that is often found in the fridge and can be white in colour. What I am?
Hint 1: I am a dairy product.
Hint 2: You can spread me on the bread.