Answer:
m∠C = 26°
m∠D = 108°
m∠E = 46°
Explanation:
Set up the equation adding the expressions together to equal 180 (sum of all angles in a triangle)
(2x) + (x+3) + (5x-7) = 180
Remove the parentheses
2x + x+ 3 + 5x - 7 = 180
Add like terms
8x - 3 -7 = 8x -4 = 180
8x - 4 = 180
Add 4 on each side to cancel it out on the right
8x - 4 = 180
+4 = +4
8x = 184
Divide each side by 8 to get the variable by itself
8/8 =1 184/8 = 23
x = 23
Substitute x in eac expression
2x = 2(23) = 46°
x + 3 = 23 + 3 = 26°
5x - 7 = 5(23) - 7 = 115 -7 = 108
Chek it by adding all the degrees to make sure it equals 180
46 + 26 + 108 = 72 + 108 = 180