Bobby is making ornaments for christmas to sell. He is selling ornaments for $9.00 each. He also just receive ed a check for $28 for some previous sales he made. If bobby sells 21 ornaments next week, what is a reasonable estimate for how much total money he received

$217.

Step-by-step explanation:

So he starts with 28 dollars. We want to find out how much total he makes. To do so we multiply 21 by 9 because he sells 21 ornaments at $9. 21 x 9 = 189. 189 + 28 = 217. So with the $28 from the start, he made $217.

1,407.5 hours

step-by-step explanation:

we first convert all the time to hours and then sum them up.

there are 24 hours in 1 day, in 58 days, there are 24 x 58 = 1,392 hours.

there are 60 minutes in 1 hour, thus, 30 minutes will be equivalent to 30 / 60 = 0.5 hours.

therefore, the number of hours it will take mercury to complete a full rotation is 1,392 + 15 + 0.5 = 1,407.5 hours