Solve the Inequality for f 3f+9<21

$3 f + 9 < 21$

Step 1

Move all terms not containing $f$ to the right side of the inequality.

Subtract $9$ from both sides of the inequality.

$3 f < 21 - 9$

Subtract $9$ from $21$ .

$3 f < 12$

Step 2

Divide each term in $3 f < 12$ by $3$ and simplify.

Divide each term in $3 f < 12$ by $3$ .

$\frac{3 f}{3} < \frac{12}{3}$

Simplify the left side.

Cancel the common factor of $3$ .

Cancel the common factor.

$\frac{3 f}{3} < \frac{12}{3}$

Divide $f$ by $1$ .

$f < \frac{12}{3}$

Simplify the right side.

Divide $12$ by $3$ .

$f < 4$

Step 3

The result can be shown in multiple forms.

Inequality Form:

$f < 4$

Interval Notation:

$(- \infty, 4)$