### Home > AC > Chapter 2 > Lesson 2.1.3 > Problem2-30

2-30.

Read the Math Notes box for this lesson. Then evaluate each expression below.

1.  For $y=2+3x$ when $x=4$, what does $y$ equal?

Rewrite the expression, substituting in the known variable.

$y=2+3(4)$
$y=2+12$

$y=14$

1.  For $a=4−5c$ when $c=-\frac{1}{2}$, what does $a$ equal?

See part (a) for a strategy to evaluate this expression. Remember to pay attention to negative signs.

$a=6.5$

1.  For $n=3d^2−1$ when $d=−5$, what does $n$ equal?

Rewrite the expression, substituting in the known variable.

$n=3(−5)^2−1$
$n=3(25)−1$
$n=75−1$

$n=74$

1.  For $v=−4(r−2)$ when $r=−1$, what does $v$ equal?

Refer to parts (a) and (c).

1.  For $3+k=t$ when $t=14$, what does $k$ equal?

Rewrite the problem, substituting in the known variable and then rearrange the problem to make it equal to the unknown variable.