Hello: Why is the answer 47 bolts and 18 nails?

The opportunity cost is, 1 bolt = 60/ 30 = 2 nails

The opportunity cost is 1 nail = 30/ 60 = bolts

For Azerbaijan is

The opportunity cost is = 80 / 20 = 4 nails

The nails opportunity cost is = 20/ 80 = bolts

What do i do next? to get to the answer Thanks

Figure 3-9 Uzbekistan's Production Possibilities Frontier Azerbaijan's Production Possibilities Frontier 100 Twin 10 10 15 30 25 30 35 40 43 30 10 15 20 25 30 35 40 45 50 Refer to Figure 3-9. If the production possibilities frontiers shown are each for two days of production, then which of the following combinations of bolts and nails could Uzbekistan and Azerbaijan together nor make in a given 2-day production period? a. 47 bolts and 18 nails b.36 bolts and 56 nails c. 9 bolts and 122 nails Od. 21 bolts and 98 nails