Answer:
Step-by-step explanation:
( 4 / 21 ) ( 7 / 16 ) ( 15 / 9 )
= ( 2 × 2 × 7 × 3 × 5 )/( 3 × 7 × 2 × 2 × 2 × 3 × 3 )
= ( 5 )/ ( 2 × 3 × 3 )
= 5 / 18
