### Home > CAAC > Chapter 2 > Lesson 2.1.3 > Problem 2-30

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

For

*y*= 2 + 3*x*when*x*= 4, what does*y*equal?For

*a*= 4 − 5*c*when*c*= , what does*a*equal?For

*n*= 3*d*^{ 2}− 1 when*d*= −5, what does*n*equal?For

*v*= −4(*r*− 2) when*r*= −1, what does*v*equal?For 3 +

*k*=*t*when*t*= 14, what does*k*equal?

Rewrite the expression, substituting in the known variable.

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

*y* = 14

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

*a* = 6.5

Rewrite the expression, substituting in the known variable.

*n* = 3(−5)² − 1*n* = 3(25) − 1*n* = 75 − 1

*n* = 74

Refer to parts (a) and (c).

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