The equation is y= mx + b, so working backwards:

y= -x

where m is the coefficient of x, we can rewrite:

-x= (-1)x

so:

m= -1

and b is missing! So we can write in a non-value for b:

b= 0

we are left with:

y= mx + b

y= (-1)x + 0

y= -x

Hi Angela! It looks like you need some help with figuring out the equation of a line. The equation for a line is y = mx + b where Y is the y variable, M is the slope, X is the x variable, and b is the intercept (or where the line crosses the Y axis). Your slope (m) is always the number that is multiplied by x (it's called a coefficient) and your intercept (b) is always the number that is added or subtracted from your x. So for y = -x your slope m is actually -1 because you have a -x and anything times 1 is itself, so in math language it's dropped and you're left with -x. Your b is going to be 0 because it's not in the equation given to you! Try this with your other questions.