Question 553719
I'm not sure why you included the division by 3. It is not needed.
.
You were correct with:
.
y + (y-3) + 3(y -3) 
.
To write the equation you can let P represent the perimeter. Then the equation is:
.
P = y + (y-3) + 3(y -3) 
.
To simplify the right side you can do the distributed multiplication of the last term by multiplying +3 times each of the terms in the parentheses to get:
.
P = y + (y-3) + 3y - 9
.
Because the remaining set of parentheses (for the second side) is preceded by a + sign, you can just remove the parentheses and you then have:
.
P = y + y - 3 + 3y - 9
.
Now add up the three terms that contain y ... y + y + 3y = 5y
.
and you have P = 5y - 3 - 9
.
Finally combine the two constants -3 - 9 = -12
.
and you have the final equation:
.
P = 5y - 12
.
and don't forget that the units for P is yards.
.
Hope this helps you to understand the problem better. You had done the hard part correctly except that there was no need to divide the last term by 3. The third side was just three times the second side, and since the second side was y - 3, you only needed to multiply 3(y - 3) to get the third side.
.
Keep up the good work ... you're getting it!!!