the length of the second side of a triangle is 3cm shorter than the first side and the third side is twice as long as the first side. if the perimeter is 49 how long are the 3 sides

I like to setup a "Let" statement when solving this type of problem.

Let x = first side (since the other sides are defined by it)

x - 3 = second side (since it is 3 cm shorter - take it away - than the first side)

2x = third side (since it is twice - 2 times - the first side)

Then we are given the perimeter which is the sum of all the sides. So we create an equation as follows.

first side + second side + third side = perimeter

x + x - 3 + 2x = 49

Solve the equation: 4x - 3 = 49

4x = 52

x = 13

We've got the first side ... use it to find the other sides

First side = 13 cm

Second side = 13 cm - 3 cm = 10 cm

Third side = 2 * 13 cm = 26 cm