How can i simplify this expression 2x-y+5x

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

What is the simplified form of (3.25x10^3)(7.8x10^6) written in scientific notation?

What is the length of the midsegment of a trapezoid with bases of length 15 and 25 ?