Tolong segera jawab no 4 ya mohon bantuannya

U1 = a = 7
U2 = a+ b = 11
b =11-7 =4

U15 = a +14b
= 7 +14.4
=7+56
=63

U1 = 7
U2 = 11
U3 = 15
b = U2 - U1 = 11 - 7 = 4.
Un = a + (n-1)b
U15 = 7 + (15-1)4
U15 = 7 + 56
U15 = 63 (A)