Let's say David's age right now is x years
x + 6 = 2(x - 7)
x + 6 = 2x - 14
x = 20
Therefor David is 20 years old
Step-by-step explanation:
Quadratic term = Coefficient of x^2 term = 3.
Answer:

Step-by-step explanation:
Associative Property


Commutative Property


Distributive Property


