Write an equation of the line shown. Then use the equation to find the value of x when y = 185. When y = 185, x = __.
a) Equation: y = 2x + 5, x = 90
b) Equation: y = -3x + 200, x = 5
c) Equation: y = 4x - 10, x = 45
d) Equation: y = (1/2)x + 80, x = 210