Cakes and sundaes

2 sundaes and 1 cupcake is $17. and 1 sundae and 1 cupcake is $10. when we remove 1 sundae from 2 sundae and 1 cupcake, we loses $7. so thats mean 1 sundae price is $7. so 2 sundae price is $14. so there is $3 left. and thats the cupcakes price.(answer)

suppose, sundae=S and cupcake=C

so, 2S+C=17...........................................(1)

and, S+C=10........................................(2)

so, S =7.............................[by subtracting equation 2 from 1]

now,   in equation 2 we get,      S+C=10


                                           or,7+C=10,         0r,C=3

17-10=7 so therefore, the answer would be seven because when subtracted from each other, there is only one cupcake left.