After how many seconds is the height 68 feet? when the equation is h=-16t2+64t+8

The table below shows the height of a ball  x  seconds after being kicked.  what values, rounded to the nearest whole number, complete the quadratic regression equation that models the data? f(x)  =  x2  +  x  +  0based on the regression equation and rounded to the nearest whole number, what is the estimated height after 0.25 seconds?   feet

To solve the system of equations below, pedro isolated the variable y in the first equation and then substituted it into the second equation. what was the resulting equation? { 5y=10x {x^2+y^2=36

Solve the following simultaneous equation by using an algebraic method (either substitution or elimination) 2x + 3y=-4 4x-y=11