20 points! .. which expression is equivalent to the given expression? −(1/2y + 1/4)

a. −1/4 (1+2y)
b. 1/4 (2y−1)
c.−2 (1/4y−1/8)
d. 2 (1/8−1/4y)

Asphere has a diameter of 10 in. what is the volume of the sphere?

1. a parachutist is 800 feet above the ground when she opens her parachute. she then falls at a constant rate of 5 feet per second. select the equation that represents this situation. h = -800t + 5 y = -5x + 800 h = 5t - 800 y = 800x + 5 i need

The serenity and the mystic are sail boats. the serenity and the mystic start at the same point and travel away from each other in opposite directions. the serenity travels at 16 mph and the mystic travels at 19 mph. how far apart will they be in 3 hours?