The mixed numbers need to be converted into improper fractions first: 4 1/2=(2*4+1)/2=9/2; 13 7/18=(18*13+7)/18=241/18; 3 5/6=(6*3+5)/6=23/6.
The equation can be rewritten: -24/7(-2n/3+9/2)-241/18-23n/6. Work out the contents of the brackets next: using the common denominator 6 we have (-4n+27)/6 or (27-4n)/6.
Now we multiply by the number outside the brackets: -24/7*(27-4n)/6=-4(27-4n)/7.
We need the lowest common denominator of 7 and 18 (6 goes into 18 so 6 will go into the LCD of 7 and 18=126 (=7*18)). The expression becomes: (-72(27-4n)-1687-483n)/126=(-1944+288n-1687-483n)/126=(-3631-195n)/126=-(3631+195n)/126=-(3631/126+65n/42).