|
Accounting | Business | Computer Science | General Studies | Math | Sciences | Civics Exam | Help/Support | Join/Cancel | Contact Us | Login/Log Out Need A Tutor? | Need Homework Help? Help and Support | Join or Cancel College Algebra
(MAC-1105C) Lesson 26
Solving Systems of Linear Equations by Substitution           Answer: 6, 12
First
move everything to the right side of the first equation except y. We do this to
create a value for y.
x + y =
18 =
y = 18 –
x
Now we
plug in the value of y, which we just created, into the second equation.
.55x +
.25(18 – x) = .35(18)
Now we
factor as far as we can and solve for x.
.55x +
4.5 - .25x = 6.3
.3x + 4.5
= 6.3
Subtract
4.5 for both sides: .3x = 1.8
Divide
both sides by .3: x = 6
So, now
that we know x = 6, we can plug in the value (of x) and solve for y.
(We only
need to do this with the first equation, although we could do the same
with the
second equation and the value would be the same).
(6) + y =
18
Subtract
6 from both sides.
y = 12
x = 6, y = 12
 Answer: 115, 30
First, plug in the Value of x which is 3y + 25 and solve for y.
3y + 25 +
y = 145
4y + 25 =
145
4y = 120
y = 30
Then plug
in the Value of y and solve for x.
x + 30 =
145
x = 115
|
| Home |
Accounting & Finance | Business |
Computer Science | General Studies | Math | Sciences |
Civics Exam |
Everything
Else |
Help & Support |
Join/Cancel |
Contact Us |
Login / Log Out |