Driving for 75 km what method would I use

Two florida panthers were weighed. one weighs 6x+21 pounds and the two together weigh 14x+11 pounds how much does he other panther weigh alone

Asquare and an equilateral triangle have the same perimeter. each side the triangle is 4 inches longer than each side of the square. what is the perimeter of the square

What is 100,000 times 1/100,000, using the standard method of multiplication? write the answer as 10 to a power.