Answer:
20
Step-by-step explanation:
The cost of the x mangoes was ...
c = 10(x/4)
The revenue from the sale of mangoes was ...
r = 20(x-5)/5
The profit is the difference between revenue and cost:
10 = r - c = 20(x -5)/5 -10(x/4) = 1.5x -20 . . . . substitute and simplify
30 = 1.5x . . . . . add 20
20 = x . . . . . . . .divide by 1.5
The trader bought 20 mangoes.
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<em>Check</em>
He paid 20(10/4) = 50 naira. He sold the 15 good mangoes for 20/5(15) = 60 naira, so made a 10 naira profit.
1.2x10^-4
When doing scientific notation the number can't be equal to or bigger than 10 so since it was 12 you had to move the decimal over one so ^-1 then since thousandth is .000 then you have to do ^-3 and then ^-1 + ^-3 is ^-4 and so it comes out 1.2x10^-4... in bad at teaching but hey now you know the answer