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Math·Algebra·Linear functions

easy

The function $f(x)=-30x+390$ gives the predicted height above the ground $f(x)$, in feet, of a model airplane $x$ minutes after it begins to descend. What is the predicted height above the ground, in feet, of the model airplane $3$ minutes after it begins to descend?

A

$90$

B

$300$

C

$360$

D

$480$