The commutative property states that, when adding or multiplying numbers, the order in which they're added or multiplied does not matter. For example, 3 + 4 and 4 + 3 give the same result, as do 3 x 4 and 4 x 3.

To add or subtract terms with exponents, both the base and the exponent must be the same. In this case they are so subtract the coefficients and retain the base and exponent:

6b⁷ - 4b⁷
(6 - 4)b⁷
2b⁷

The hourly error rate for this machine is the error rate in parts per 100 multiplied by the number of parts produced per hour:

\( \frac{9}{100} \) x 6 = \( \frac{9 \times 6}{100} \) = \( \frac{54}{100} \) = 0.54 errors per hour

So, in an average hour, the machine will produce 6 - 0.54 = 5.46 error free parts.

The machine ran for 24 - 5 = 19 hours yesterday so you would expect that 19 x 5.46 = 103.7 error free parts were produced yesterday.

By buying two shirts, Ezra will save $35 x \( \frac{50}{100} \) = \( \frac{$35 x 50}{100} \) = \( \frac{$1750}{100} \) = $17.50 on the second shirt.

So, his total cost will be
$35.00 + ($35.00 - $17.50)
$35.00 + $17.50
$52.50

To add or subtract terms with exponents, both the base and the exponent must be the same. In this case they are so add the coefficients and retain the base and exponent:

2x⁶ + 9x⁶
(2 + 9)x⁶
11x⁶