Answer
$x = (25~m/s^4)~t^4+ 3~m$
Work Step by Step
In general, a straight line has this form:
$y = mx + b$
$m$ is the slope
$b$ is the vertical axis intercept
We can use the information in the question to write the linear equation:
$x = (25~m/s^4)~t^4+ 3~m$