HI could someone help me with this question? Thank you very much
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A tip: Just solve & solve it, you will end up having solution.
At first,
On comparing, we can say that,
Put e = f - 10 in 4e = 9f
Put f = -8 in equation(i) to find the value of e;
And finally we have got f = -8 & e = -18, now let procede futher;
Thus, our final answer is 180.