how do i solve this problem?

Question

4x+5y=8
x=3y-15

Answer 1

4x+5y=8
x=3y-15

you first have to rearrange your equations
by this:

4x+5y=8 ...............(eq.1)
x-3y=15...............(eq.2)

then,
multiply (eq.2) by 4, becomes,

4x-12y=60 ............(eq.3)

subtract (eq.3) by (eq.1) you have,

4x-12y=60
4x+5y=8
---------------------
-17y=52
divide 52 by -17 to get the y,

y=(-3 and 1/17) answer is in mixed
fractions.
or y= -3.058823529


to get the value of x,
substitute the value
of y in the (eq.2),

x-3y=15...........(eq.2)
x=15+3y
x=15+3(-3 and 1/17)
x=15+(-9 and 3/17)
x=(5 and 14/17) answer is in mixed fractions.
or x= 5.823529412

To prove that the answers are correct,
you have to substitute the value of the two
fractional answers to the (eq.1) and (eq.2)

4x+5y = 8..............(eq.1)

4(5 and 14/17) + 5(-3 and 1/17) = 8
8=8 answer is correct!



x-3y=15..............(eq.2)
(5 and 14/17) -3(-3 and 1/17) = 15
15=15 answer is correct!


alright.....k.

Answer 2

equation (1) 4x+5y=8
equation (2) x=3y-15

Substitute x in equation (1)
4 (3y - 15) + 5y = 8
12y - 60 + 5y = 8
17y = 60 + 8
17y = 68
Divide both sides of the equation by 17
y = 4

Substitute the value of y in equation (2)
x = 3(4) - 15
x = 12 - 15
x = -3

Answer 3

First, bring your 3y over to the x side.....you now have x-3y=-15.
You need to cancel out either your x's or your y's. I'm going to cancel out my x's. To do this, I multiply by -4....

4x+5y=8
-4(x-3y)=-15*-4

You now have the equations, and
Now you do as the signs indicate....
4x+5y=8
-4x+12y=60 =
0 +17y= 68
17y = 68
y=4

Do the same to find x.....cancel out your y's by multiplying ur first equation by 3 and your second equation by 5.

Answer 4

you know what x is in terms of y.

Use the substitution rule.

4(3y - 15) = 8
12y - 60 = 8 (distributive property)
12y = 68
y = 17/3

Substitute value of y into the second equation

x = 3 (17/3) -15
x = 17 - 15 = 2

Answer 5

sub 3y -15 in for x in the first equation

4(3y-15)+5y=8
12y-60+5y=8
17y=68
y=4

Put that value in the second equation

x=3(4)-15
x=12-15
x=-3

(-3,4)