The answer to the question
This is a typical work problem in algebra. The approach to this is using the equation: Rt = 1, where R is the rate per person working, t is the amount of time worked by an individual. All their rates must equal to 1. The solution is as follows:
12/x + 15/x = 1
Solving for x,
x = 27 hours
So, if they work together, they can finish the work in 27 hours.
180-106=74
X is congruent to 2y
x=74
74/2= 37
y=37
(4z+6) is congruent to 106
106-6= 100
100/4 = 25
z=25