What will the following code output to the console?

const obj $=\{$

$$ x: $10,$

$$ y: $20,$

$$ z: $\{$

$$ a: $5,$

$$ b: $15,$

$\},$

$$ calculate: function$()\{$

$$ let sum $=$ this.x $+$ this.y;

$$ for $($let key in this.z$)\{$

$$ sum $+=$ this.z$[$key$]$;

$\}$

$$ return sum;

$\}$

$\}$;

console.log$($obj$.$calculate$())$;

$50$

$45$

$25$

$30$

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