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

\( \frac{8}{100} \) x 8 = \( \frac{8 \times 8}{100} \) = \( \frac{64}{100} \) = 0.64 errors per hour

So, in an average hour, the machine will produce 8 - 0.64 = 7.36 error free parts.

The machine ran for 24 - 6 = 18 hours yesterday so you would expect that 18 x 7.36 = 132.5 error free parts were produced yesterday.

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:

-2a⁴ + 7a⁴
(-2 + 7)a⁴
5a⁴

If the tiger has consumed 91 pounds of food in 7 days that's \( \frac{91}{7} \) = 13 pounds of food per day. The tiger needs to consume 156 - 91 = 65 more pounds of food to reach 156 pounds total. At 13 pounds of food per day that's \( \frac{65}{13} \) = 5 more days.

A ratio of 2:1 means that there are 2 home fans for every one visiting fan. So, of every 3 fans, 2 are home fans and \( \frac{2}{3} \) of every fan in the stadium is a home fan:

42,000 fans x \( \frac{2}{3} \) = \( \frac{84000}{3} \) = 28,000 fans.

By buying two shirts, Ezra will save $18 x \( \frac{45}{100} \) = \( \frac{$18 x 45}{100} \) = \( \frac{$810}{100} \) = $8.10 on the second shirt.