5% of $30 is (5/100)*30 = $<<(5/100)*30=1.5>>1.5
The dollar amount of Bob's discount is $1.5 so he will pay $30-$1.5 = $28.5
2% of $25 is (2/100)*$25 = $<<2/100*25=0.5>>0.5
The dollar amount of Kate's discount is $0.5 so she will pay $25-$0.5 = $<<25-0.5=24.5>>24.5
Altogether they will pay $28.5+$24.5 = $<<28.5+24.5=53>>53
#### 53