Answer:
Iron: 280m³
Zinc: 105m³
Tungsten: 35m³
Step-by-step explanation:
8+3+1 = 12
(8/12)×420 = 280
(3/12)×420 = 105
(1/12)×420 = 35
20a (less than or equal to) 28a
PEMDAS
2a + 3= 5a
4*5a=20a
2. a+1=1a
-3*1a=-3a
-3a+31= 28a