posted by Jodi .
The perimeter of an equilateral triangle is 7 in. more than the perimeter of a square. The side of the triangle is 5 in. longer than the side of the square. Find the length of each side of the triangle. (Note: An equilateral triangle has all sides equal)
Let x be the triangle's side length and y be the square's side length.
3x = 4y + 7
x = y + 5
Solve those two simultaneous equations. One way would be to substitute y+5 for x in the first equation. This would give you
3y + 15 = 4y + 7
which leads to y=8 etc.
side of the triange is 20 while side of the square is 15