This is the standard form of the equation. You have to make it into slope-intercept form to find the slope, hence the name.
7x+2y=5
7x+2y=5.
-7x. -7x. (You need to have y=)
2y=-7x+5.
/2. /2. (Divide by 2 to get only 1 y)
y=-7/2x+2.5. (Final Answer)
The slope is -7/2.