Step-by-step explanation:
9. x and z are equal. y+z=90
    148-x=180 x+148 are supplementary
    -148    -148 Subtract 148 from both sides to isolate x
          x=32 degrees
          z=32 degrees b/c x and z are equal
  y+z=90 y and z are complementary
  y+(32)=90 Substitute 32 in for z
    -32     -32
  y         =58 degrees
10. (4x-25)=(2x+7) B/c of the bisection, the two angles are equal.
      4x-25  =2x+7 Remove parenthesis
       -2x       -2x Subtract 2x from both sides
      2x-25  =    +7
           +25       +25 Add 25 to both sides to isolate x
     2x         =     32
      /2                 /2 Divide both sides by 2 to isolate x
      x            =     16
  (4(16)-25)+(2(16)+7)=78 degrees Substitute 16 into the equation, this time adding the values instead of setting them equal to get the angle measure requested.
11. (6x-47)+(x+4)=90 Angles that are complementary add up to 90 degrees
     7x-43            =90 Add like terms
          +43             +43 Add 43 to both sides to isolate x
    7x                    =133
    /7                       /7 Divide both sides by 7 to isolate x
      x                     =19
((19)+4)=23 degrees Substitute x into the angle measure requested
12. 180=2x-9+x Use the words to help you determine what each value is.
      180=3x-9 Add like terms
      +9        +9 Add 9 to both sides to isolate x
      189=3x
      /3     /3 Divide both sides by 3 to isolate x
      63=x
  2(63)-9=177 degrees Substitute 63 into x to find the requested angle measure.