Question 37 metamorphic rocks the protolith of a metamorphic rock a. is always metamorphic rock to begin with b. is always igneous rock c. is always sedimentary rock d. may belong to any of the three primary rock types

d. may belong to any of the three primary rock types

Explanation:

Metamorphic rock is the transformation of any of the existing rocks through the process of metamorphism i.e associated with changes in form. When the original rocks are subject to intense heat from below. The Pressure over these rocks causes profound hearing and compaction of rocks particles and matter. About 12% of the earth's surface is made up of metamorphic rocks that are either derived from the igneous or sedimentary rocks based on texture, chemical, and mineral assemblage.  Some common examples of these rocks are gneiss, slate, marble, and schist, etc that have been formed from the sedimentary processes.

5×^2+20-15 or -(5x^2-20+15)

Economy is the answer