1. Let's clarify the question: You want to understand how the number $-1$ becomes $+1$ in the context of coordinates $(x,y)$, specifically in step 3 of a problem. 2. In coordinate pairs $(x,y)$, the sign of each number depends on its position and the operation applied. 3. If you have an expression like $-(-1)$, the two negatives cancel out, resulting in $+1$. 4. For example, if step 3 involves $y = -(-1)$, then by the rule $-(-a) = +a$, it becomes $y = +1$. 5. This is because the negative sign outside the parentheses negates the negative inside, turning it positive. 6. So, the $-1$ turns into $+1$ due to the double negative sign, not just by being in $(x,y)$ form. 7. Always look for operations like negation or subtraction that can change the sign. 8. If you provide the exact expression from step 3, I can explain more precisely.