Video Transcript
A diver began his ascent to the
surface. He ascended 20 meters to his next
decompression stop and must ascend another 32 meters to return to the surface. Write and solve a subtraction
equation to find the diver’s original depth before he started ascending.
The diver started at a depth that
we don’t know. We can call this step 𝑥. We do know that the diver ascended
20 meters and still needs to ascend 32 meters before the diver reaches the
surface. We want to write and solve a
subtraction equation to find 𝑥, the diver’s original depth. If we began with 𝑥, the diver is
𝑥 meters deep and he rises 20 meters. Mathematically, we need to
represent that with subtraction because he is not as deep as he was before. Even though he’s going up, he is
becoming less deep. It’s his original depth minus the
20 meters he rose. And 𝑥 minus the 20-meter ascent
will equal the 32 meters that remain, which means one equation is 𝑥 minus 20 equals
32.
To solve this equation, we add 20
to both sides. 32 plus 20 equals 52. And so, we can say that the diver’s
original depth was 52 meters. We’ve written a subtraction
problem. And we’ve solved for the missing
depth to show that the diver’s original depth before he started ascending was 52
meters.
