well in order to find the slope the equation should be in y= mx +b format, where m=slope
to do this you take your equation,
7x=-3y+15
and notice how the x and y are in the wrong position ,
add the 3y to both sides and subtract 7x from both sides
7x=-3y+15
+3y +3y
7x+3y=15
-7x. -7x
3y=-7x+15
now we need the y to be by itself so we divide the entire equation by 3 and get
y=-7/3x+5
so -7/3 or 2.33 or 2 1/3 would be the slope, the slope of parallel lines are equal
