Question

Qual deve ser o capital aplicado à uma taxa de juro simples de 25% a.a. para quem tem 6 meses renda 425,00 de juro ?

Answer 1

para calculo de juros usamos a formula J = P . i . n  e nesse caso nos preenchemos os valores na formula para descobrirmos a icognita:

J = P . i . n

425 = P . 0,25 . 6

425 = P . 1,5

P = 425/1,5

P = 283,33333... reais (arredondando 283,33 reais)

Answer 2

$\sf\large \boxed{\boxed{\tt J = C \cdot i \cdot t}}$

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$\sf \displaystyle 425\:=\:C\:\cdot 0,\:25\:\cdot \left(\frac{1}{2}\right)\\\\\\\sf \boxed{\star \sf \ {Troque \:os \:lados} }\\\\\\\sf C\cdot \:0.25\left(\frac{1}{2}\right)=425\\\\\\\sf C\frac{0.25}{2}=425\\\\\\\sf 2C\frac{0.25}{2}=425\cdot \:2\\\\\\\sf 0.25C=850\\\\\\\sf \frac{0.25C}{0.25}=\frac{850}{0.25}\\\\\\\\\large \to \boxeed{\boxed{\sf C=3400}}$