Muriel collects rainwater in a large barrel that weighs 20 pounds. when there are 10 gallons of water in the barrel, the total weight of the barrel and the water is 103.4 pounds. when there are 20 gallons of water, the total weight is 186.8 pounds.

see explanation

step-by-step explanation:

a

(6r + 7) + (13 + 7r) ( remove brackets and collect like terms )

= 6r + 7 + 13 + 7r

= 13r + 20

b

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13 - r - 1 + r

= 12 - r

c

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= - 8 - r + 2r - 4

= - 12 + r

d

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= 7r - - - 6r

[-   - = - - = - ]

= r -