Since they give us the equation they have gotten for the line of best fit, we use it to estimate what thye answer is when x = 25:
Use:
y = 1.708 x - 4.011
then when x = 25:
y = 1.708 (25) - 4.011
y = 38.689
I don't read if the want you to round the answer to a given number of decimals, but if you try exactly the number we got (with the three decimals) that would be the most exact.