The answer is -13.8y
First subtract 1.8y from 9.3y which is 7.5y, but since you are actually subtracting a larger number from a smaller number, you add a negative sign because your answer is less than 1. Then you add -6.3y to to -7.5y because you have two negatives. While it may seem like you should add them, you will subtract because you are adding essentially more negative to the negative number. I hope that makes sense! Once you add -6.3y to -7.5y your answer is -13.8y.