Can some one out with this question and give explanation

-2 1/4=r-4/5
-9/4=r-4/5  (just change the mix fraction to improper)
-9/4+4/5=r-4/5+4/5 (add 4/5 to both sides to cancel out on the right side)
-45/20+16/20=r (found common denominator to be 25)
-29/20=r (just subtracted -45 and 16, and kept the denominator the same)
-1 9/20 changed to mixed fraction

Sure, 
-2 1/4=r-4/5
1. Convert 2 1/4 to improper fraction. Use this rule_ a b/c = (ac+b)/c
-(2*4+1)/4=r-4/5

2. Simplify 2*4 to 8
-(8+1)/4=r-4/5

3. Simplify 8+1 to 9
-9/4=r-4/5

4. Add 4/5 to both sides
-9/4+4/5=r

5. Simplify -9/4+4/5 to -29/5 
-(9*5)/(4*5) + (4*4)/(5*4)
-45/20 + 16/20
(-45+16)/20
-29/20
r=-29/20
r=-1.45

Have a nice day :D