if miguel and jian are splitting the bill then it would have to be x+y=75 because they are each paying their amounts lets say that jian pays 35 and miguel pays 40 that would make the total pay 75. if you had to go the other answers it wouldnt make sense example A:35=40+70 that is incorrect unless the restaurant only accepted spicific currency that the 2 didnt have and even then it would be over paying for C:3540 would mean that they are paying using a foren currancy that uses larger numbers for smaller amounts of pay as for D:35/40=75 that answer is not even mathmatically correct as an amount like that would not equal 75 no matter what way you put it without putting 75/1 although correct it says and implys that they split the bill almost evenly so D is also wrong