Answer:
h - 145 = 457
602 meters
Explanation:
The original height of the helicopter is unknown.
Let h = original height of the helicopter.
The helicopter was originally at height h.
The helicopter descended 145 m.
Descending means going down, so it lost height, so we subtract 145 from the original height.
The helicopter is now at a height of h - 145.
The new height is 457 meters.
That means that h - 145 must equal 457.
The equation is
h - 145 = 457
This is a subtraction equation since the only operation is the subtraction on the left side.
To solve the equation, we want h alone on the left side. 145 is being subtracted from h. The opposite operation to subtraction is addition. If we add 145 to the left side, we get h - 145 + 145 which is just h. That's what we want. We must do the same operation to both sides of an equation, so we add 145 to both sides.
h - 145 + 145 = 457 + 145
h = 602
Since h stands for the original height, now we answer that the original height was 602 meters.