dasgurke: HI!
I hope I got your question right, because I'm not a native speaker.
Let's pretend your three sides are called (side 1) x, (side 2) z, (side 3) y.
z is given as x+5
y is given as z*2
and if I got that right, x is given as 75.
so x = 75 .
y is asked.
z = x + 5
z = 75 + 5
z = 80
y = z * 2
y = 80 * 2
y = 160
Correct me if I'm wrong
The question asked :
"The seccond side of a triangle measures 5 in longer than the first side and the third side is twise as long as the seccond. The perimeter is 75 in. Find the third side."
Okay you were mistaken on x. 75in is the perimeter. A perimeter is all the sides added together.
First side = X
second side = X+5
third side = 2(x+5)
You can use y and z, but it just makes things more complicated.
Perimeter = 1st side + 2nd side + 3rd side
so
x + x + 5 + 2(x+5) = 75
Order of operations multiply first
x + x + 5 + 2x + 10 = 75
Combine like terms
4x + 15 = 75
Solve for x
4x=60
x= 15
Then answer the question. They want the third side.
Third side = 2(x+5)
2(15+5) = Side3 = 40 inches
Hope this helps,
<3 Ivy
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