Question

Na compra de um aparelho tive um desconto de de 15% por pagar à vista. Se paguei 102 reais qual era o preço original?

Answer 1

100 - 15 = 85%
85/100 = 0.85 representa  102 reais
102 : 0.85 =120.00

Answer 2

$\sf \bullet \underbrace{\sf Veja \to}\\\\\\\tt 85x=102\cdot100\\\\\\\tt 85x=10200\\\\\\\tt\dfrac{85x}{85}= \dfrac{10200}{85}\\\\\\\to \boxed{\tt x=120R\ \ PRE\c{C}O\ NORMAL}$