Backward-bending labour supply curve, is a graphical device showing a situation in which as real (inflation-corrected) wages increase beyond a certain level, people will substitute leisure (non-paid time) for paid worktime and so higher wages lead to a decrease in the labour supply and so less labour-time being offered for sale.
In this case Zambrano will choose such point of budget line and indifference curve intersection, at which he can get more leisure than worktime.
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