Question

Greg has decreased his running time by 1/10 minute each of the last six weeks. Write an expression to represent the total change in his time over the last six weeks. Then, find the total change.

Answer 1

x is your starting running time. 1/10 of a minute is 6 seconds, so you can do x - 6(6). 6 times 6 = 36, so your answer is x - 36 seconds. 36 seconds.

Answer 2

Total change = x - 36 seconds.

Explanation:

Let Greg's initial running time be x seconds.

Also, 1/10 minute = 6 seconds.

In the first week, his running time = x - 6

In the second week, his running time = x - 6 - 6 = x - 2(6)

In the third week, his running time = x - 6 - 6 - 6 = x - 3(6)

....

....

In the sixth week, his running time = x - 6(6) = x - 36

Hence, the total change = x - 36.