How do I do the math for this I haven't been taught. A basketball is thrown upward from a height of 6 feet at an initial speed of 15 feet per second. As the basketball travels, Earth's gravity slows it down.

The height of an object dropped from a height of 6 feet is given by h(t)=−16t2+6.

The distance in feet traveled by an object at a constant speed of 15 feet per second is given by d(t)=15t.

These two functions can be combined to build a new function, f, that models the height of the basketball as a function of time in t seconds.

Which choice shows how to combine h and d to build f