The number of boxes of pizza is 8 + 10 = <<8+10=18>>18 boxes.
The number of cans of soda is 10 + 15 = <<10+15=25>>25 cans.
The eighteen boxes of pizza cost 18 x $14= $<<18*14=252>>252.
The cost of 25 cans of soda is 25 x $1.80= $<<25*1.8=45>>45.
Therefore, the total amount they spend is $252 + $45 = $<<252+45=297>>297
#### 297