The answer should be b. 12
First calculate his gross salary after his 401k contributions:

Then find the amount of taxes withheld:

5,760 dollars went towards taxes.
4x+2y=10 Equation 1
x-y=13 Equation 2
Solving by substitution method.
Isolate x from equation 2.
x=y+13
Substitute value of x in equation 1
4(y+13)+2y=10
4y+52+2y=10
6y+52=10
6y=-42
y=-7
Now substitute value of y in x=y+13
x=-7+13
x=6
Answer: (6,-7)
1/4 is equivalent to 5/20
Find the area of the shaded rectangle and then the second. Subtract them from eachither giving you the proper area of the shade grey rectangle