Can I get the working out of user' question

Can someone check if i did this correct. it’s number 4 if you’re wondering.

2x minus y equals 6, x plus y equals negative 3

Gabriel determined that his total cost would be represented by 2.5x + 2y – 2. his sister states that the expression should be x + x + 0.5x + y + y – 2. who is correct? explain.