A pupil's working gives -8 + 5 - (-3) as -6, reading the closing double sign as one more subtraction. What is the correct value?

Explication

Additions and subtractions are worked through from left to right, so eight below zero plus five gives three below zero, and taking away three below zero adds three back and lands exactly on zero. Reading the closing pair of signs as a subtraction moves those three the wrong way and lands six below zero, while reading every term as a fall totals sixteen below zero.