Can you help me I will mark you brainiest if you awnser all of them please put work into this

8. There are a total of 208 marbles in the bag.

EXPLANATION:
9/7 = 117/x solve for x

across multiply 9 with x and 7 with 117
9 x (x) = 9x
7 x 117 = 819

then you get 9x = 819 and you divide that
9x = 819
÷ 9 ÷9

the you get your x
x = 91

then add your original 117 and 91 to get 208
117 + 91 = 208
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9. The plane would travel about 93.3 miles in 20 minutes.

EXPLANATION:

We know that the plane goes 280 miles per hour. And we only want one third of that hour (20 minutes). So you would just divide 280 by 3.

60 minutes (1 hour) = 280 miles

÷ 3. ÷ 3 divide by 3

20 minutes ≈ 93 miles
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10. 67 cm

EXPLANATION:
You use the surface area formula for a rectangular prism which is A=2(wl+hl+hw)

A = 2·(0.5·7+4·7+4·0.5) fill in the blanks

(0.5·7+4·7+4·0.5) add your values together

A = 2 (33.5) multiply and find your answer

A = 67 cm
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11. 174 mm

EXPLANATION:
First find the missing lengths. To find height of the bottom rectangle you would just do 15-9 which equals 6, and for the width you would add 14 + 6 which equals 20.

15mm - 9mm = 6mm
14mm + 6mm = 20mm

After you have all of your sides, you can do separate the rectangles to do the area formula. A = (L)(W)

A = (15mm)(6mm) which equals 90mm
A = (14mm)(6mm) which equals 84mm

Next you add the two sums together, and you have your area!

90mm + 84mm = 174mm
A= 174mm
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12.

EXPLANATION:
To find the mean of a data set, all you have to do is all of the numbers together, and divide by the amount of numbers in the data set.

1+4+8+12+4+10+15 = 54

54 ÷ 7 ≈ 7.7
Mean ≈ 7.7
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sorry it’s a lot :)

The answer would be 24mm