2. He can break his strand of 10 blocks into 3 3 times 4. I think it is 74 blocks are needed.
Divide I from both sides then subtract r from both sides, too so in the end:
R= (E-r)/I
Switch the x and y values and isolate y, then simplify.
x=6y+5
6y=x-5
y=1/6x-5/6
(9+w)w=252 or w(w+9)=252.
The quadratic equation applies: w²+9w-252=0=(w+21)(w-12), so w=12, because a negative zero is meaningless.
So the dimensions are width=12 in and length=21 in.
