How do i become smarter in math class and im in 8th grade

Aprojectile is thrown upward so that its distance above the ground after t seconds is given by the function h(t) = -16t2 + 704t. after how many seconds does the projectile take to reach its maximum height?

Which expression demonstrates the use of the commutative property of addition in the first step of simplifying the expression (-1+i)+(21+5i)+0

Awoman who is 64 inches with a shoulder width of 16 inches. write an equation relating the height h to the width w. find the height of a woman who has ashoulder width of 18.5 inches