Formula: 45*(X-0.4)+40*X= 135.

Solution: x = 1.8 hours.

(2) Let the second bus travel from A to B for x hours.

Formula: 30 * (x+2) = 45 * x.

Answer: x = 4 hours

(3) You must get an X in math.

Formula: (87.5+97+X)/3=95.

Solution: x = 100.5

(4) let the length of forged steel be x.

Formula: 5 * 5 * 5 = 2.5 * 2 * X.

Solution: x = 25 decimeters

(5) Set another car to travel x kilometers per hour.

Formula: (38+X)*3.5=280

Solution: x = 42

(6) Let the first pile be x tons and the second pile be (37-X) tons.

Formula: x = 4 * (37-x)+4.

Solution: x = 30.4 tons

(37-x) = 6.6 tons