nomer 18-21 plisss! pkk cara

18) V = r × r × r
658.503 = r³
r = ³√658.503
r = 87 dm ( B )

19) 2 dasawarsa - 2 windu + 2 semester
= ( 2 × 10 ) - ( 2 × 8 ) + ( 2 × ½ )
= 20 - 16 + 1
= 5 tahun ( D )

20) 10 m³ + 20.000 cm³ - 20 dm³
= ( 10 × 1.000 ) + ( 20.000 ÷ 1.000 ) - 20
= 10.000 + 20 - 20
= 10.000 liter ( A )

21) 10.10 - 07.30 - 00.20
= 02.20
= 2 jam 20 menit ( A )