Answer: y = 5/2 x + 5 or more clearly: 
Step-by-step explanation: Slope intercept form y = mx + b
m is the slope, b is the y-intercept
To write the equation for a perpendicular line
Both lines could share the y-intercept, (0,5) so the "b" term can be the same. But it may be different. The slope of a perpendicular line is the reciprocal of the original slope with the opposite sign.
So invert 2/5 to become 5/2 and change the negative sign to positive.
The resulting equation is y = 5x/2 + 5 or y = 2.5x + 5