Question

Emilio owns a bakery. The number of boxes of cookies he has left on a Monday is represented by the function x + y = 42, where y is the number of boxes of cookies remaining in the bakery and x is the number of hours since he opened the bakery. How many boxes did he have at the start of business on Monday?

Answer 1

Since "x" is defined as the time, you could also set x=0, representing the very start.
So
\[\Large 0+y= 42\]
\[\large y=42\]

So there were 42 boxes at the start, time 0.