Class A has 13 pupils and class B has 30 pupils. Both classes sit the same maths test.
The mean score for class A is 45.
The mean score for both classes is 66.
What is the mean score (rounded to 1 DP) in the maths test for class B?
quickest answer gets brainliest :))

step-by-step explanation:

try remembering the steps

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step-by-step explanation:

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see explanation

step-by-step explanation:

a

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

= 6r + 7 + 13 + 7r

= 13r + 20

b

remove brackets and collect like terms

13 - r - 1 + r

= 12 - r

c

remove brackets and collect like terms

= - 8 - r + 2r - 4

= - 12 + r

d

remove brackets and collect like terms

= 7r - - - 6r

[-   - = - - = - ]

= r -

you just switch the numbers basically so it would be 3/17