The perimeters of the rectangle and triangle shown below are both equal.

x=0.4

perimeter of rectangle and perimeter of triangles is 7.6 each

Step-by-step explanation:

2(7x-1.8)+2(4x+1.2)=perimeter of rectangle

6x+0.4+4x+6x+0.08=perimeter of triangle

since the perimeters are equal then

2(7x-1.8)+2(4x+1.2)=6x+0.4+4x+6x+0.8

14x-3.6+8x+2.4=16x+1.2

22x-1.2=16x+1.2

22x-16x-1.2+1.2=16x-16x+1.2+1.2

6x=2.4

x=0.4