Answer: 3/8 of the chocolate was left uneaten
Step-by-step explanation:
The original chocolate bar is assumed to be 1
Sam eats 1/2 of a chocolate bar. It means that the remaining portion of the chocolate bar would be
1 - 1/2 = 1/2
Jack eats 1/4 of the remaining chocolate bar. This means that the portion of the chocolate bar that Jack ate is
1/4 × 1/2 = 1/8
The total portion of chocolate bar that Sam and Jack ate is
1/8 + 1/2 = (1 + 4)/8 = 5/8
Therefore, the portion of chocolate that is left uneaten is
1 - 5/8 = 3/8
