You can isolate y and you know that the slope is the number in front of x (the one that multiplies it)
You know that the y-intercept is the value of y when x=0, therefore you can find y by replacing x with 0 in the equation
1-equation
5x-8y=3
5x=3+8y
5x-3=8y
(5x-3)/8=y
y=(5/8)x -3/8
(Slope = 5/8)
2- y-intecept (x=0)
y=(5/8)(0)-3/8
y=-3/8