Answer:
x=6
Step-by-step explanation:
Since a square's sides are all congruent, the perimeter for the square is:
(x+3)4= 4x+12 P of square= 4x+12
Since an equilateral triangle's sides are all congruent, the perimeter is:
2x(3)= 6x
Since it says the perimeters are equal,
6x=4x+12
2x=12
x=6
