Answer:
418
Step-by-step explanation:
fig 2 = fig 1 + 5
fig 3 = fig 2 + 7 or fig 1 +5+7 16
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
4+5+7+9+11+13+15+17+18+19+21+23+25+27+29+31+33+35+37+39
