Please help I don’t understand

How to write 3 tenths and 5 tenths as a decimal

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

The table shows the balance of a money market account over time. write a function that represents the balance y(in dollars) after t years.