Question 622433
so the side of one square will be x and the length of the other square is going to be x+3, 

now we know the total perimeter is going to add up to 76cm, and the formula for perimeter of a square is {{{P=4L}}}

so for total perimeter is going to be the perimeter of the two squares ass, hence,
{{{Tp=4x+4(x+3)}}}
{{{76=8x+12}}}
{{{64=8x}}}
{{{x=8}}}