Answer
$-3$
Work Step by Step
We start with the given expression: $90-3x$
We plug in the given value for $x$: $90-3(31)$
Order of operations states that first we perform operations inside grouping symbols, such as parentheses, brackets, and fraction bars. Then, we simplify powers. Then, we multiply and divide from left to right. Then, we add and subtract from left to right We follow order of operations to simplify:
First, we multiply: $90-93$
Then, we subtract: $-3$