1 70%
Toilet rolls come in packs of 4 and 9.
The 4-pack is priced at £2.25.
The 9-pack is priced at £4.50.
By calculating the price per roll, determine which pack is better value.
Show your working.

what does 1 and 70% mean in this question

38 was the other number of your question.

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.