Why is multiplying by three and 6 the same?

Aladder that is 20ft long is leaning against the side of a building. if the angle formed between the ladder and the ground is 75 degrees how far is the bottom of the from the base of the building?

Rationalize the denominator- 12x/√x-10

Edger needs 6 cookies and 2 brownies for every 4 plates how many cookies and brownies does he need for 10 plates