The value of b is?

[AAPL]

In the figure above, the value of b is?

A. 20
B. 40
C. 42
D. 80
E. 100

The OA is B.

This PS question can be solved in the following way,

(5a) + (4a) = 180, then a = 20.

And (4a) = (b + 40) (vertically opposite), also we can say (b + 40) + (5a) = 180.

Finally, b = 40.

Is there a strategic approach to this question? Can any experts help? Thanks!

[Jeff@TargetTestPrep]

In the figure above, the value of b is?

A. 20
B. 40
C. 42
D. 80
E. 100

We can create the equation:

5a + 4a = 180

9a = 180

a = 20

and

b + 40 = 4a

b + 40 = 4(20)

b + 40 = 80

b = 40

Answer: B