Hi there!
Voltage in a series can be expressed by the following:

In words, the total voltage is equal to the sum of the individual voltage drops in a SERIES circuit.
We can solve for the total voltage:

I do a yoga mat that could be different to your answer
Subduction is, "<span>the sideways and downward movement of the edge of a plate of the earth's crust into the mantle beneath another plate." The basalt would most likely be swallowed up into the ground.
Hope this is what you were looking for! :)
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