First, we need to create an equation for this problem.
5(25 mm ÷ 4 m)
Now, all you have to do is solve it. Remeber, you would start in the parenthesis using the distributive property (PEMDAS).
5(25 mm ÷ 4 m)
5 × 6.25 = 31.25 mm
The length of the blueprint would be 31.25 millimeters.
I hope this helps!