Question

determine o preço de 18kg de batata se,2/5kg custam 24 reais?

Answer 1

2/5 de kg = 24 reais então 400g = 24 reais
18/2/5 = 45 * 24 = 18kg custa 1125R$

Agora se for 2/5 for igual a 2,5kg
18/2,5 = 7,2 * 24 = 172, 80 R$

Answer 2

2/5 * 1000g = 2000/5 = 400g

400g custam 24 reais
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18 kg = 18 * 1000g = 18000 g 
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18000 / 400 = 45


45 * 24 = 1080
18 kg custam 1080 reais