Question

for 8 days of very hot weather, the water level in a lake dropped 3 inches per day. on the ninth day, storms raised the level 6 inches. Write and find the value of an expression for the change in the water level of the lake during these 9 days.

Answer 1

-(3*8)+6=-18

the water level decreased by 18 inches.

Answer 2

During the span of 9 days, the water level of lake decreased by 18 inches.

Explanation:

We are given the following information in the question:

For 8 hot days, the water level decreased in a lake at rate of 3 inches per day.

Then on day 9, there was a storm that increased the water level by 6 inches.

Total drop in water level in lake =

`\text{Number of days}* \text{Rate of drop in water level per day}\\= 8* 3\text{inches per day}\\=24\text{ inches}`

Expression for the change in the water level =

`\text{Increase in water level in 9 days} - \text{Decrease in water level during 9 days}\\=6 - 24\\ = -24 + 6 = -18\text{ inches}`

Hence, during the span of 9 days, the water level of lake decreased by 18 inches.