Question 1138423
(60, 1600) & (150, 5200) points (u, P).


{{{b=(5200-1600)/(150-60)=40}}}

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{{{P-1600=40(u-60)}}}

{{{P=40(u-60)+1600}}}

{{{P=40u-2400+1600}}}


{{{highlight(P=40u-800)}}}
COMPARE THIS TO YOUR EQUATION'S FORM:  P(u) =a+ bu
or compare it with P=-800+40u.
You see now?



Next questions, you just USE the equation found.


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1.2. Break-even level 
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Profit is 0, so let P(u)=0 and solve for u.


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1.3. Number of units that need to bbe sold to realise a profit of R12 000.
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That means, P(u)=12000; solve for u.