Solve for the unknow variables in the matrix equation.

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.

so the rectangle is 80cm (area)

now to find the area of a triangle.

base times height.

4 times 8.

your answer is 96cm.

hope this .

here the answers ur welcome also plz mark as brainliest if someone else anwers