Hmm you seem pretty smart how about now?

Hmmm... 
If he presses the button 5 times then the length will be 3.2

His boss said that if he presses five times then it will be smaller than the desired length therefore he shouldn't press five times... that is the correct answer

The answer is D.)
Javier's boss and he should not press the button five times

Hope this helps :P

Hi Meep21, 

3(7x - 9) - 19x = - 15
21x - 27 - 19x = - 15
2x = 27 - 15
2x = 12
x = 12 / 2
x = 6

S = {6}

x + 3(x - 7) = 19
x + 3x - 21 = 19
4x = 19 + 21
4x = 40
x = 40 / 4 
x = 10

S= {10}