Yes, 13 is the remainder.
See dat pic for full solution.
<u><em>The additive identity property </em></u>. . . is being used here because no matter what the value is, whenever you add zero (0) to it, you'll always get the value your started with.
Try to put x on one side.
Do y = 35+X
-35 -35
Now you have Y-35=x
Hope this helped
100°+(4y+25)+(3y+20)=180°
100+4y+25+3y+20=180
7y+145=180
7y=35
y=5
100°; 45°; 35°
92
29
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first times 9 by 2 then 9 by 9
then add a 0 for the second colum as a place holder then 2 times 2 and 9 times 2 add the two colums together