Please help me (10 points)

What expression is equivalent to 1/2(2+3x-6)

You are standing next to a really big circular lake. you want to measure the diameter of the lake, but you don't want to have to swim across with a measuring tape! you decide to walk around the perimeter of the lake and measure its circumference, and find that it's 400\pi\text{ m}400? m. what is the diameter dd of the lake?

Jonathan can throw a baseball 10 1/3 yards. his brother joey can throw a baseball 13 1/2 yards. how much father can joey throw the ball?