9. a) (-4/5)*(12/12) + (7/12)*(5/5) =
(-48/60) + (35/60) =
-13/60
b). (5/9)(4/4) - (1/4)(9/9) =
(20/36) - (9/36) =
11/36
c). (-3/7)(11/12) = -33/84
divide top and bottom by 3
= -11/28
d). -1 2/3 = -5/3
(-5/3)(4/5)= -20/15
divide by 5
= -4/3
10. a) 6x-3+2=5x
6x-1=5x
subtract 6x from both sides
-1=-x
divide both sides by -1
1=x
b). subtract 600x from both sides
200= -100x
divide both by -100
-2 = x