wash + iron      = Rp 34.150
wash - iron      = Rp 14.150
iron - wash      = -Rp 14.150
3 * iron         = Rp 30.000
10% of the sum   = Rp 3.415
big amount       = Rp 1.234.567.890
till             = Rp 29.150
wash == iron     : false
iron <  wash     : true
till >= sum      : false
[     Rp 24.150]
[Rp 24.150     ]
