The answer is 38cm.
The formula used is perimeter of rectangle so in this case it will be 2(PQ+QR).
So,
=2×(12+7)
=2×19
=38cm
The value of A is 144 degrees
For one block every minute, it should be 24 minutes and for 2 blocks per minute, it should be 12 minutes.
A common way to simplify this problem would be to use an area model, or the distributive property. Using the distributive property does not require any drawing, so here goes.
(x-3)(x²+7x-8) Distribute by multiplying each of the terms in the first set of parentheses by every term in the second set of parentheses.
x³+7x³-8x-3x²-21x+24 Then combine alike terms.
8x³-3x²-29x+24 Is your final answer.