Answer:
The sides have lengths: 29,18, and 33
Step-by-step explanation:
Let the first side have a f (meters);
the second side a length of s (meters)
and the third side a length of t (meters)
The first side of a triangle is 7 cm shorter than twice the second side.
f=2s-7
2s=f+7 Get b by itself by dividing by 2
s=(f+7)/2
The third side is 4 cm longer than the first side.
t=f+4
The perimeter is 80 cm.
f + s + t = 80
Replace s & t using the above equations
f+(f+7)/2+(f+4)=80 get rid of that annoying fraction, multiply by 2, results
2f + (f+7) + 2(f+4) = 2(80)
2f + f + 7 + 2f + 8 = 160 Combine like terms a's and constant
5f + 15 = 160 Subtract 15
5f = 145 Divide 5
f=29 is side f then
s=(29+7)/2 Add 29 and 7 together
s=36/2
s=18 is side s and
t= 20+4
t=33 is side t
To double check to make sure they add to 80
29+18+33=80