Answer:
y = 7x
Step-by-step explanation:
The equation of a line passing through the origin is
y = mx ( m is the slope )
Calculate m using the slope formula
m = 
with (x₁, y₁ ) = (0, 0 ) and (x₂, y₂ ) = (100, 700 ) ← 2 points on the line
m =
=
= 7
y = 7 x ← equation of line