Answer:
Graph of the new function will be vertically stretched by 2 units.
Explanation:
A linear function is represented by the equation, y =

This function has the slope =
and y-intercept = 4
If this function is stretched vertically by 'k' the the equation of the new function will be,
y =

y =
---------(1)
If the slope of this equation is changed to
,
New equation of the function will be,
y =
---------(2)
Comparing equations (1) and (2),
a = 2
Therefore, graph of the new function will be stretched vertically by 2 units.