An equation for the line perpendicular to the line 4x + 8y = 7 having the same y -intercept as −3x + 5y = −2

4x + 8y = 7
8y = -4x + 7
y = -1/2x + 7/8 this equation has slope = -1/2

line perpendicular to the line 4x + 8y = 7, so the slope = 2 

same y -intercept as −3x + 5y = −2 
 y intercept means x = 0
 5y = −2 
 y = -2/5
so
b = -2/5
 

 equation: 

y = 2x - 2/5