Step-by-step explanation:
the usual equation for a line is
y = ax + b
a is the slope. it is always the factor of x and is expressed as ratio y/x. this indicates how many units y changes, when x changes a certain amount of units when moving from one point to another.
(0, -3.2) is one point. and (4, 0) is another.
x changes by +4 (from 0 to 4).
y changes by +3.2 (from -3.2 to 0)
the slope is therefore
3.2/4 = 32/10 / 4 = 32/40 = 4/5
b is the y-intercept. that is the point, where the line crosses the y-axis (the y value when x = 0).
the given point specifies this already.
so, the line equation of the lower line is
y = (4/5)x - 3.2 or (4/5)x - 32/10 or (4/5)x - 16/5
the upper line is parallel, so the slope is the same.
and what is b, the y-intercept ? we see that the line goes directly through the origin (0, 0). so, b = 0.
the line equation of the upper line is
y = (4/5)x
