Write an equivalent expression using an associative law.

$$-7(a b)$$

Find the absolute value. |13|

Multiply and simplify. Leave the answer in exponential notation.

$$t^6 \cdot t^0$$

Determine the area of a triangular flag that has a base of $50 \mathrm{~cm}$ and a height of $70 \mathrm{~cm}. \quad$

Solve. $I=\operatorname{Prt}$, for $r$ (a formula for interest)

Simplify.

$$8 x+2[x-(x-1)]$$

Find whether the two equations in the pair are equivalent. $3 x-4=8$ and $3 x=12$

Convert to scientific notation.

$$0.000078$$

Write an equivalent expression using an associative law.

$$(3 x) y$$

Write an equivalent expression using a commutative law. The solution may vary.

$$(7 x) y$$

Write an equivalent expression using a commutative law. The solution may vary.

$$-9(a b)$$

Write an equivalent expression using a commutative law. The solution may vary.

$$4 a+7 b$$

Write an equivalent expression using a commutative law. The solution may vary.

$$6+x y$$

Compute using the rules for the order of operations. If an expression is undefined, state this.

$$43-(-9+2)^2+18 \div 6 \cdot(-2)$$