Unit A rejects 8% of the pieces it makes and unit B rejects 5% of the pieces it makes. Unit A's rejection rate is what per cent higher than unit B's?

Compare the two rates as numbers: (8 - 5)/5 = 3/5 = 0.60, so A's rate is 60% higher than B's. 3% is the gap in percentage POINTS, which is what most people quote and is not what 'what per cent higher' asks for. 37.5% is 3/8, the comparison turned round - it says B's rate is 37.5% lower than A's, which is a true but different statement. 160% is 8/5, A's rate as a per cent OF B's rather than how much higher it is.