Question 1013118
4x+1+7x-11+11x-16=84
22x-26=84
22x=110
x=5
It helps to draw this.  I have MN as the base and P to the upper right of N. Angle A is P, angle B is M, angle C is N.  Law of Cosines
MN is 21 (A)
NP=24  (B)
MP=39  C)  C will be the biggest angle
c^2=a^2+b^2-2abcosC
1521=441+576-2(504) cos C
504=-2(504)cos C
cos C=-(1/2)=120 degrees.
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a^2=b^2+c^2-2bc cos A
441=576+1521-2(936) cos A
-1656= -1872 cos A
cos A=27.8 degrees  Can assume the other angle is 32.2 but will check to be sure.
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b^2=a^2+c^2-2ac cos B
576=441+1521-2(819) cos B
-1386=-1638 cos B
cos B=32.2
The angle at N is the largest, the one at M the second largest, and the one at P the smallest.