Answer:
The winning ticket is: A.
.
Explanation:
We have been given that Tomas’s math class held a raffle. The student who picked the ticket with a pair of equivalent equations on it would win.
Let us check our given pairs of equations one by one.
A.
![x^2-3xy+4-2x^2=-x^2-2xy-xy+4](https://img.qammunity.org/2019/formulas/mathematics/college/4s45zbz8yxjjk023qjg5jgtwhp0do0l61y.png)
Let us combine like terms on the both sides of our equation.
![(x^2-2x^2)-3xy+4=-x^2-(2xy+xy)+4](https://img.qammunity.org/2019/formulas/mathematics/college/jtlv4letbxnj1wnimw0pniowt1cc5m8rnl.png)
![(-x^2)-3xy+4=-x^2-(3xy)+4](https://img.qammunity.org/2019/formulas/mathematics/college/j57ognihwthwqd1dm10vvkayu0iwwmq1mc.png)
We can see that both sides of our equation are equal, therefore, option A is the correct choice.
B.
![7y^2-yz+4-2yz=7y^2-2yz+4yz](https://img.qammunity.org/2019/formulas/mathematics/college/hjngl13jzmwfiaj88x9n2ohb50gftqzh1x.png)
Let us combine like terms on the both sides of our equation.
Since the both sides of our equation are not equal, therefore, option B is not a correct choice.
C.
![3a^2-ab+3-3ab=6a^2-2ab+3-2ab](https://img.qammunity.org/2019/formulas/mathematics/college/g41l6jluir1jvxplplcjc35otlbs87g958.png)
Upon combining like terms we will get,
![3a^2-(ab+3ab)+3=6a^2-(2ab+2ab)+3](https://img.qammunity.org/2019/formulas/mathematics/college/l1gy1pop0d8aj2jua80i1iczojoopena6g.png)
![3a^2-(4ab)+3=6a^2-(4ab)+3](https://img.qammunity.org/2019/formulas/mathematics/college/nfvkjicbcz1o6umkljqfd0fr2u4ek10wxd.png)
![3a^2-4ab+3\\eq 6a^2-4ab+3](https://img.qammunity.org/2019/formulas/mathematics/college/kx0pz4egmi606lezoctnbxzbuexleqli3k.png)
Since the both sides of our equation are not equal, therefore, option C is not a correct choice.
D.
![9s^2-st+5-3st=6s^2-3st+5+3s^2](https://img.qammunity.org/2019/formulas/mathematics/college/xsef8wwakckmvywclieh3fd9bt2tavyfrg.png)
Upon combining like terms we will get,
![9s^2-(st+3st)+5=(6s^2+3s^2)-3st+5](https://img.qammunity.org/2019/formulas/mathematics/college/4yeflg1yhhjy3rja9tkh7fv3egwuiowd3b.png)
![9s^2-(4st)+5=(9s^2)-3st+5](https://img.qammunity.org/2019/formulas/mathematics/college/fwi6lidh8ri4ngp9ghz07boen6mohcm1g3.png)
![9s^2-4st+5\\eq 9s^2-3st+5](https://img.qammunity.org/2019/formulas/mathematics/college/o0x1lcwg83tl21lclod5xvxsu1r0gldg9a.png)
Since the both sides of our equation are not equal, therefore, option D is not a correct choice.