tolong di jawab pertanyaan ini

U5 = a + 4b = 14
U8 = a + 7b = 29
------------------------- -
               -3b = -15
                  b = 5

a + 4b = 14
a + 4(5) = 14
a + 20 = 14
a = 14 - 20
a = -6

a) suku pertama = -6
    beda  = 5

b) U12 = a + 11b
            = -6 + 11(5)
            = -6 + 55
            = 49

c) U10 = a + 9b
            = -6 + 9(5)
            = -6 + 45
            = 39
   
   S10 = 10/2(-6+39)
          = 5 (33)
          = 165