Answer:
Arlo's weight = 52.3 kg
Explanation:
Let Arlo be "x"
Then,
Arlo = x
Bert = x+20 (Because Bert is 20 heavier than Arlo)
Cassie = x+20-5 (Because Cassie is 5 lighter than Bert)
Donnie = 
(Because Donnie is half of Bert's weight)
Average = 57
Step by step Calculations:
57 = 
(The whole divided by 4 because the total people is 4)
57*4 = x + x + 20 + x + 20 - 5 +
228 = 3x + 35 +
228 - 3x - 35 =
193 -3x =
2(193 - 3x) = x + 20
386 - 6x = x + 20
386 - 20 = x + 6x
366 = 7x
x = 
x = 52.3 kg (corrected to 3 significant figures)
Therefore Arlo's weight is 52.3 kg
900/1200 = 0.75
75%
The first year was 75% of the second year
Your fractions are your units and rates.
A "section" is a unit and 2 of 9 sections is a rate.
An hour is a unit and 1 of 10 hours is a rate.
You can multiply the fractions and create a new unit rate that would measure a section per hour.
I hope this helps.
You would add 9 to -6 and the answer to that is equal to X. X=3
1:a would be 3. Subtract 9 & 6 to find 3. B= 7. Again 9-2 would help you find the answer. So then it would be 3+6=7+2.
2: 2+8 gets you 10. 10+5 gets you 15. 8+5 gets you 13. 2+13 gets you 15. So it’s 15=15.
3:7 needs to be changed into a fraction so, 7/1(1/7). Multiply across, you get 7/7, which gives you 1, so it’s 1=1.
4:I’m sorry I don’t know how to do this one
5:you multiply 3 and 6x, which gives you 18x. Then multiply 3 and 9y, and you get 27y. So then you have 18x+27y=18x+27y.
6: 15+0 gets you 15. So it’s 15=15.
Hope this helped. I’m not the best at explaining
