Algebra problem please help..........................?
please show me how to do this please 
A triangle has a perimeter of 165 cm. The first side is 65 cm less than twice the second side. The third side is 10 cm less than the second side. Write and solve an equation to find the length of each side of the triangle.
Comments
ok, so u know P= 165, and that is what all the sides together will equal.
now, make a let statement (let x= ...) to show the information of the sides.
I'm going to use "x" as my variable.
Now, one side of the triangle has to be your plain variable, and since we know the least amount of information about side 2, that will be my plain variable. so...
let x= side two
let 2x - 65 = first side
(this is because the problem tells you that, to find side 1, you must multiply the second side (x) by 2 then subtract that by 65)
let x- 10= third side
(because the problem say that the 3rd side is 10 cm shorter than the 2nd side, which is "x"
now, you have to use all the information to make an equation
Since the normal equation for finding perimeter for a triangle is P= side 1 + side 2 + side 3, that is the formula we will use, and all we have to do is substitute the parts of the problem
165 = x + (2x - 65) + (x - 10)
get ride of the parenthesis:
165 = x + 2x - 65 + x - 10
put the like terms next to each other:
165 = x + 2x + x - 65 - 10
combine like terms:
165 = 4x - 75
move the 75 over to the other side of the equal sign. (165 + 75) (because the 75 is being subtracted you must add 75 to each side, and the -75 and 75 will cancel each other out)
240 = 4x
divide 4 from each side (because it is being multiplied by "x")
60 = x
side 1 = 55
side 2 = 60
side 3 = 50
done. sorry it's so long, i hope it helped
Let 2nd side have length x
1st side = 2x -65
3rd side = x -10
So 2x-65 + x + x-10 = 165
4x -75 = 165
4x = 165 +75 = 240
x = 60
Therefore the sides have length 55 cm , 60 cm , 50 cm .
Let x = length of the first side.
.....y = length of the second side.
.....z = length of the third side.
Then,
x + y + z = 165
x = 2y - 65
z = y - 10
Substituting,
(2y - 65) + y + (y - 10) = 165
2y + y + y = 165 + 65 + 10
4y = 240
y = 60
x = 2(60) - 65
...= 55
z = y - 10
...= 60 - 10
...= 50
x = second side
(2x - 65) = first side
x - 10 = third side
x + 2x - 65 + x - 10 = 165
4x = 240
x = 60
p=165
second side = x
first side = 2x-65
third side = x-10
165 = 4x-75
240 = 4x
60 = x
first side = 2(60) -65 = 55
second side = x = 60
third side x-10 = 50
check
55 + 60 + 50 = 165
x = second side
(2x - 65) = first side
x - 10 = third side
x + 2x - 65 + x - 10 = 165
4x = 240
x = 60
A + B + C = 165
A=(2B) - 65
C=B -10
[(2B)-65] + B + (B-10) = 165
4B - 75 = 165
4B = 240
B = 60
A = (2x60) - 65 = 55
C = 60 - 10 = 50