If by markup you mean discount then.....
1.5*0.07 = $0.105
That must be a very good pen ;D
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Answer to a1=6.8
a2= 0.5
mean is 6.78
i don’t know the rest sorry
6 / (x+1) = 1/2
x +1 = 12
x = 11
Answer is d ....(11)