Answer: y = 
x + 7
Explanation:
 First, we will write the given equation in slope-intercept form. To do this we will isolate the y-variable.
 2x + 3y = 21 ➜ y = -
x + 7
 A perpendicular line will have the negative reciprocal as it's slope. Then, we will substitute the given coordinate point to solve for the y-intercept.
 y = mx + b
 y = 
x + b
 4 = 
(-2) + b
 4 = -
 + b
 4 = -3 + b
 7 = b
 Lastly, we can create our equation.
 y = mx + b
 y = 
x + 7