The sum of two numbers is 33. the sum of the smaller and 3 times the larger is 81. find the numbers.

Define x  and y :

Let the small number be x. 
And the big number be y.


Construct equations :

The sum of the 2 numbers is 33.
⇒ x + y = 33

The sum of the smaller number and 3 times the larger number is 81.
⇒x + 3y = 81


Find x and y :

x + y = 33    (1)
x + 3y = 81 . (2)


Equation (2) - (1) :

2y = 48
y = 24


Sub y = 24 into equation (1) :

x + y = 33
x + 24 = 33
x = 33 - 24
x = 9


Find the two numbers :

Smaller number = 9
Bigger number = 24


The two numbers are 9 and 24.

The two numbers are 9and 24

-2x + 7 = 7

subtract 7 from both sides.

-2x = 0

divide both sides by -2.

x = 0

the value of x is equal to 0.

The answer to your question is b