Sagot :
180 = y + y + 30 + 40
180 = 2y + 70
180 - 70 = 2y
110 = 2y
y = 110/2
y = 55
180 = 2y + 70
180 - 70 = 2y
110 = 2y
y = 110/2
y = 55
the sum of triangle is 180:
[tex]y + 40 + y + 30 = 180 \\ 2y + 70 = 180 \\ 2y = 180 - 70 \\ 2y = 110 \\ y = \frac{110}{2} \\ y = 55[/tex]