91Ó°ÊÓ

Tell whether the given value of the variable is a solution of the equation.

$21-z=-  4;  z=25$

Solve the equation. Check your solution.

$-1.8u=6.3$

What is the coefficient of y in the expression$8−3y+1$

For the given expression,identify the terms, like terms, coefficients, and constant terms. Then simplify the expression.

$\text{ }−7b+3+b−10$

Explain how the commutative and associative properties of multiplication can help you evaluate the product $5  ·  17  ·  2 $ mentally

Drilling One type of thermal ice drill can drill through ice at a rate of 15 feet per minute by using heat to melt the ice. Find the time it takes the drill to melt through a sheet of ice 75 feet thick.

Simplify the expression.

$9t-3\left(3t-2\right)$

Astronomy Cepheid stars appear to pulsate because they expand and contract in size. In its contracted phase, the Cepheid star Zeta Geminorum is 51 million miles across. This is 5 million miles less than the star’s distance across in its expanded phase. Find the distance across Zeta Geminorum in its expanded phase.

Geometry The figure shown is composed of a triangle and a rectangle.

a. Write and simplify an expression in terms of x for the area of the figure.

b. What is the value of x if the area of the figure is 154 square feet?

Extended Problem Solving You are making a rectangular rug. You want the rug to be twice as long as it is wide. Let w represent the width (in feet) of the rug.

a. Write an expression in terms of w for the perimeter of the rug.

b. Write an expression in terms of w for the area of the rug.

c. Calculate Copy and complete the table.

d. Writing Explain how doubling the width of the rug affects the perimeter and the area