If I give two chocolate bars to Tião, he will lend me his bicycle for 3 hours. If I give him 12 chocolates, he will lend me the bicycle for 2 hours. Tomorrow, I will give him one chocolate bar and 3 chocolates. For how many hours will he lend me the bicycle?
(a) $1 / 2$
(b) 1
(c) 2
(d) 3
(e) 4
The correct option is (c).

Given $\left\{\begin{array}{l}2 \text { bars give } 3 \text { hours} \\ 12 \text { chocolates give } 2 \text { hours}\end{array}\right.$, it follows that $\left\{\begin{array}{l}1 \text { bar gives } 1.5 \text { hours }=1 \text { hour } 30 \text { minutes} \\ 3 \text { chocolates give } 0.5 \text { hours }=30 \text { minutes}\end{array}\right.$

Thus, Tião will lend me the bicycle for $1 \text { hour } 30 \text { minutes } + 30 \text { minutes } = 2$ hours.