You just have to make 36/10 into 3 6/10. After that, it would become 3.6
36 × 24 = 864 square inches. 864 sq in × $0.05 = $43.20. The green poster cost $43.20
12 × 18 = 216 square inches. 216 sq in × $0.05 = $10.80. The red poster cost $10.80
Please mark brainliest