91Ó°ÊÓ

An inequality can be solved by isolating the variable on one side of the inequality.

Each multiple-choice question is worth 4 points and each true-false question is worth 3 points. Marco answers 14 multiple-choice questions correctly.

Let Marco answer x true-false questions correctly.

Then, he answers 14 multiple-choice questions correctly, each worth 4 points each and x true-false questions correctly, each worth 3 points each.

Then his total score is $4\left(14\right)+3x$.

According to the problem, his total score should be at least 80.

Then, by the problem,

$4\left(14\right)+3xâ‰\yen 80$

This is the required inequality.

$4\left(14\right)+3xâ‰\yen 80$ (Obtained inequality)

$56+3xâ‰\yen 80$ (Simplify)

$56+3x-56â‰\yen 80-56$ (Subtract 56 from both sides)

$3xâ‰\yen 24$(Simplify)

$\frac{3x}{3}â‰\yen \frac{24}{3}$ (Divide both sides by 3)

$xâ‰\yen 8$ (Simplify)

This implies that he must answer at least 8 true-false questions correctly to get at least 80 points total.