Question

A scuba diver descends 80 feet, rises 25 feet, descends 12 feet, and then rises 52 feet where he will do a safety stop for five minutes before surfacing. At what depth did he do his safety stop?

Answer 1

let's think of distance above sea level as a positive number, then we must

think of going below sea level as a negative number. Going up is in the

positive direction while going down is in the negative direction. Give all

the descending distances a negative sign and the ascending distances a

positive sign.

The resulting numerical expression would be

as follows: −80 + +25 + −12 + +52

Because addition is commutative, we can

associate like-signed numbers. (−80 + −12) + (+25 + +52)

Evaluate the numerical expression in each

parentheses. [−80 + −12 = −92]

[+25 + +52 = +77]

 

Substitute the values into the numerical

expression. (−92) + (+77)

Are signs different? Subtract the value of the

numbers and give the result the sign of the

higher value number. [92 − 77 = 15]

The diver took his rest stop at −15 feet.

The diver took his rest stop at −15 feet.