19.

19. Area      =   length ´ width


6x - 3    =    2x - 1 ´ width
width     =    6x - 3
            

Ans : C

20. Extend AB to meet EC at G



Ð BGE = b                              [alternate angle]
Ð BGC = 180 - b                    [linear pair]
Ð GBC = 180 - a                    [linear pair]
Ð BGC + Ð GBC + Ð BCG     =    180
            180 - b + 180 - a + c     =    180
                    a + b - c

Ans : B

21.       a     =    first term


             =    14 - 8
             =     6
      t_n    =    a + (n - 1) d

where n  =   9, d   =  common difference    =    8
         t9  =     6 + (9 - 1) ´ 8
              =    6 + 8 ´ 8
              =    70

Ans : A

22. If triangles are similar


Ratio of Areas = Square of Ratio of sides/ altitudes


                 A(DDEF)   =    16 ´ 8

                                   =   128

Ans : D

23. The distance between base of mountain & sea - level


       = (2200 - 1500) - 250
       = 700 - 250
       = 450


Ans : B

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