Question 93458
You should probably already know that complementary angles equal 90 degrees together, so angle a + angle b = 90.
[90 = angle a + angle b]
90 = 3x-7 + 11x-1      
[Group like terms (3x and 11x; -7 and -1)]
90 = 14x-8             
[Add 8 on both sides]
98 = 14x     
[Divide both sides by 14]          
x = 7                 
Then "plug and chug" as my teacher used to say.
Angle a = 3(7)-7
a = 21 - 7
a = 14 degrees
Angle b = 11(7)-1
b = 77 - 1
b = 76 degrees
Check again just to make sure the angles equal 90 degrees together.
14 + 76 = 90
They match up, so you know your answer is correct!