Math with a boy and a girl

Use variables instead of pictures

Let girl = g
Let boy = b

2g - 4/b = 10 => (*b) => 2gb - 4 = 10b => 2gb - 10b = 4

2g + 2/b = 4 => (*b) => 2gb + 2 = 4b => 2gb - 4b = - 2

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combined

2gb = 4 + 10b
=> 4 + 10b - 4b = -2 => 6b = -6 => b = -1 (Boy = -1)

now 2g + 4 = 10 => 2g = 6 => g = 3 (Girl = 3)

in total the reuslt 3 - (-1) = 4

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