A. . Any number could work as long as the coefficients for x and y stays the same. You are basically imposing that the quantity 2x-4y (if you bring 4y to the LHS) is equal to both -3 AND , or any number you like. But yesterday was 3/14 so let's pick a fun number!
B. Or . Or as long as you don't pick the same ratios of x and y you're golden. But x=1 is the easiest that comes to mind
C. . To get infinitely many solutions you just have to rewrite the equation again. Maybe move things around if you prefer, or multiply everything by a number you lile.
We need to find the perimeter of the rectangular blanket in this case because a border is being sewn onto the blanket. The perimeter of a rectangle can be calculated by multiplying the sum of the rectangle's length and width by 2. As an algebraic expression, that would be , where is the rectangle's length and is the rectangle's width. We are given that and . Therefore, cm of ribbon will be needed. Hope this helps!