Answer:
First mechanic worked 20 hours and second mechanic worked 5 hours
Step-by-step explanation:
Let the number of hours the first mechanic worked =
Let the number of hours the second mechanic worked =
Therefore, we can write 2 equations and then solve them simultaneously:
Rearranging the first equation:
and substituting into the second equation to find :
Now sub into the first equation to find
Therefore, first mechanic (a) worked 20 hours and second mechanic (b) worked 5 hours
Answer:
Second choice:
Fifth choice:
Step-by-step explanation:
Let's look at choice 1.
I'm going to subtract 1 on both sides for the first equation giving me . I will replace the
in the second equation with this substitution from equation 1.
Expand using the distributive property and the identity :
So this not the desired result.
Let's look at choice 2.
Solve the first equation for by dividing both sides by 2:
.
Let's plug this into equation 2:
This is the desired result.
Choice 3:
Solve the first equation for by adding 3 on both sides:
.
Plug into second equation:
Expanding using the distributive property and the earlier identity mentioned to expand the binomial square:
Not the desired result.
Choice 4:
I'm going to solve the bottom equation for since I don't want to deal with square roots.
Add 3 on both sides:
Divide both sides by 2:
Plug into equation 1:
This is not the desired result because the variable will be squared now instead of the
variable.
Choice 5:
Solve the first equation for by subtracting 1 on both sides:
.
Plug into equation 2:
Distribute and use the binomial square identity used earlier:
.
This is the desired result.