What is the focal length of the lens? given magnification and distance

[RedLego]

Homework Statement

A biology student wishes to examine a bug at a magnificaiton of +5.00 by looking through a single lens. the student wants the image of the bug to be a distance of 25cm from the lens. what is the focal length of the lens?

Answer:+6.25cm

Homework Equations

m=-d(image)/d(object)
1/f=$\frac{1}{d(object)}$+$\frac{1}{d(image)}$

The Attempt at a Solution

first i solve for distance of object, d(object), by using the first equation:
d(object) = (25x10^-2)/5

then i calculated focal length by using the second equation
f = ((1/0.5) + (1/0.25))^-1 = 0.041667

i don't know what I am doing wrong

 

[technician]

This is a simple magnifying glass using a converging lens.
The image is VIRTUAL...what does this mean about the image distance in the equation?