Ignore the negative sign for now.
3.75
Split the number into its whole number component and decimal component
3.75 = 3 + 0.75
For the decimal component, 0.75 is the same as 75/100
75/100
Find the GCF (Greatest Common Factor) of 75, 100
GCF = 25
Divide both the numerator and the denominator by the GCF
75 ÷ 25/100 ÷ 25
Simplify
3/4
Combine the whole number component with the fraction
3 3/4
Add the negative sign back
-3 3/4