Tolong sangattttt, makasihh

5000 + 5500 + 10000 + …..+ U25
suku pertama a = 5000, beda b = 500
Sn = n/2 { 2a + (n -1)b }
S25 = 25/2 { 2. x 5000 + (25-1) x 500 }
= 25/2 ( 10.000. + 12.000)
= 25/2 (22.000)
= 275.000,-