Solve the system of equations.

15x + 31y = -3

X = -y + 3

Will give brainliest what is the value of x? enter your answer in the box.

Solve for n? [tex]z = \frac{3}{4} mn[/tex]

The perimeter of an equilateral triangle is 4 cm more than the perimeter of a square and the length of a side of the triangle is 8 cm more than the length of a side of the aware. find the length of a side of the equilateral triangle