Bobby and $9 per hour and $6 for each delivery he makes. He wants to earn more than $155 an 8 hour work day. What is the least number of deliveries that Bobby must make to reach his goal?

Solution:

Given that,

Bobby per $9 per hour and $6 for each delivery he makes

Let "D" be the number of delivery he makes

He wants to earn more than $155 an 8 hour work day

Thus a inequality is framed as:

Subtract 72 from both sides

72 + 6D - 72 > 155 - 72

6D > 83

Divide both sides by 83

D > 13.83

Thus least number of deliveries that Bobby must make to reach his goal is 14

large crystals result from very slow cooling.

evaporation of water: this would produce an evaporite which is a sedimentary rock. like a salt pan in a desert. not possible to have volcanic rocks originate this way.

crystalization in molten earth: slow cooling over time. (hundreds to millions of years)

crystalization at earth's surface: this results in fast cooling. (a few hours to a few months or years)

crystalization from cooling off hot water: that would be a hydrothermal deposit. while associated with volcanics they are not volcanic rocks themselves and usually occur fairly rapidly.