A town has accumulated 5 inches of snow, and the depth is increasing by 6
inches every hour. Another town has accumulated 9 inches of snow, and the depth is
increasing by 3 inches every hour.
How long until the snowfall in both cities is equal?

A. 1 hour and 20 minutes
B. 1 hour and 33 minutes
C. 45 minutes
D. 1 hour 15 minutes

Therefore, after 1 hour and 20 minutes, the snowfall in both cities was equal to 13 inch.

Step-by-step explanation:

Calculating the depth of First Town:

First town has accumulated 5 inches of snow.

As the depth is increasing by 6  inches every hour

i.e. 6 inch  = 1 hour

so the depth increase after 45 minutes i.e. 3/4 hour  =  4.5 inch

so

After 45 minutes

Snow level of First town after 45 min = 4.5 + 5 = 9.5 inch

After 1 hour

Snow level of First town after 1 hour = 5 + 6 = 11 inch

After 1 hour and  20 minutes

5 + 6 + 2 = 13 inch     ∵ If 6 inch per hour, then 2 inch in 20 min

Calculating the depth of Second Town:

Second town has accumulated 9 inches of snow.

As the depth is  increasing by 3 inches every hour.

i.e. 3 inch  = 1 hour

so the depth increase after 45 minutes i.e. 3/4 hour  = 2.25 inch

so

After 45 minutes

Snow level of Second town after 45 min = 9 + 2.25 = 11.25 inch

After 1 hour

Snow level of Second town after 1 hour = 9 + 3 = 12 inch

After 1 hour and  20 minutes

Snow level of Second town after 1 hour and 20 minutes

9 + 3 + 1 = 13 inch   ∵ If 3 inch per hour, then 1 inch in 20 min  

From the above observation, it is clear that after 1 hour and 20 minutes the snowfall in both cities was equal.

Therefore, after 1 hour and 20 minutes, the snowfall in both cities was equal to 13 inch.

When rates are expressed as a quantity of 1, such as 2 feet per second or 5 miles per hour, they are called unit rates. if you have a multiple-unit rate such as 120 students for every 3 buses, and want to find the single-unit rate, write a ratio equal to the multiple-unit rate with 1 as the second term.

Atranslation 6 units to the right and 4 down