ka please ka tolong kasih tau caranya dan jawabanya ka please!!!!!!

6.
a = 15
U5 = 23
a + 4b = 23
15 + 4b = 23
4b = 8
b = 2

S5 = 5/2 (15 + 23) = 5/2 x 38 = 5 x 19 = 95

7.
U3 = 18
ar² = 18
U6 = 486
a x r pangkat 5 = 486
ar² x r³ = 486
18 x r³ = 486
r³ = 27
r = 3 dan a = 2

U8 = a x r pangkat 7 = 2 x 3 pangkat 7 = 1458

8.
25% x harga beli = harga jual - harga beli
0,25 x harga beli + harga beli = 5.000.000
1,25 x harga beli = 5.000.000
harga beli =4.000.000

#semoga membantu