tolong dikerjain nomor 15 pake caranya

hambatan pengganti pararel
1/Rpararel = 1/R1 + 1/R2 + 1/R3
1/Rpararel = 1/30 + 1/40 + 1/60
1/Rpararel = (samakan penyebut yaitu 120)
1/Rpararel = 4/120 + 3 /120 + 2/120
1/Rpararel = 9/120
1/Rpararel dikalikan silang dengan 9/120
120 = 9Rpararel
Rpararel = 120/9 = 13,3 Ohm
okay