5% of the 200 cakes they make will spoil.  That's (0.05)(200) = 10 cakes that
will spoil.

So they will only be able to sell 200-10 or 190 cakes.

It's going to cost them (200)($2.35) = $470 to make the 200 cakes.

The 40% profit they want to make will be (0.40)($470) = $188.

So they want to be able to take in $470 + $188 = $658.

So they want to sell 190 cakes and take in $658.

So they will have to sell each cake at $658÷190 = $3.463157895 each,
 
Even though the rule says we should round down to $3.46 each, that
would give a small amount less than the 40% markup, so they'll have to
charge $3.47 each, which will give them a little more than 40% markup.
                       
Edwin