Two pairs of jeans cost $40 x 2 = $<<40*2=80>>80.
A discount of $80 x 10/100 = $<<80*10/100=8>>8 will be given for this.
Hence, the cost of two pairs of jeans will now be $80 - $8 = $<<80-8=72>>72.
Therefore, the customer will pay $72 + $40 = $<<72+40=112>>112 for the three pairs of jeans.
#### 112