1/4(r-5/2)=1/8 i need an answer cant figure it out

The lines shown below are parallel. if the green line has a slope of -1, what is the slope of the red line?

Can someone check if i did this right since i really want to make sure it’s correct. if you do you so much

Moira has a canvas that is 8 inches by 10 inches. she wants to paint a line diagonally from the top left corner to the bottom right corner. approximately how long will the diagonal line be?