Three trains - one eastbound, one westbound, and one northbound - leave a city at the same time. The speed of the northbound train is 20 miles per hour greater than the speed of the eastbound train.

After 9 hours, the distance between the westbound train and the eastbound train is 990 miles.

question: how many people can she serve?

answer: she can serve 16.66666667 people. so she can only give 16 people a complete serving.

question: does she have enough ice cream for her guests?

answer: no. explanation: she only has enough for 16 people to have a full serving. however, she can give a 17th person a partial serving.

explanation:

infrared radiation has wavelength in the range between 700 nm and 1 mm. lets' convert these values into scientific notation, keeping in mind that:

let's start from the lower value, we have:

(we moved the dot two places to the left, so we increased the exponent by 2 units, from -9 to -7)

the higher value is:

so, the range of wavelength of infrared radiation is:

x= cost per bracelet

number of bracelets * x + shipping charge = total cost

so

9x+9=72