(1950 -1500)×10% +500×5%
=45 +25
=70(元)小周
(2350 - 1500)×10% +500×5%
=85+25
=110(元)老张
小周70元,老张110元
小周:500*5%+(1950-1500)*10%=70
老张:500*5%+(2350-1500)*10%=110
小周:(1950-1500)*10%+500*5%
老张:(2350-1500)*10%+500*5%
小周1950-1000x0.05+1950-1500x0.1
老张2350-1000x0.05+2350-1500x0.1