Whakaoti i te 2*90^circ+(n-2)*120^circ=(2n-4)*90^circ

$$2 \times 90 ^ { \circ } + ( n - 2 ) \times 120 ^ { \circ } = ( 2 n - 4 ) \times 90 ^ { \circ }$$

Whakaoti mō n

$$n=5$$

Ngā Upane mō te Whakaoti Whārite Rārangi

Whakareatia te 2 ki te 90, ka 180.

$$180+\left(n-2\right)\times 120=\left(2n-4\right)\times 90$$

Whakamahia te āhuatanga tohatoha hei whakarea te n-2 ki te 120.

$$180+120n-240=\left(2n-4\right)\times 90$$

Tangohia te 240 i te 180, ka -60.

$$-60+120n=\left(2n-4\right)\times 90$$

Whakamahia te āhuatanga tohatoha hei whakarea te 2n-4 ki te 90.

$$-60+120n=180n-360$$

Tangohia te 180n mai i ngā taha e rua.

$$-60+120n-180n=-360$$

Pahekotia te 120n me -180n, ka -60n.

$$-60-60n=-360$$

Me tāpiri te 60 ki ngā taha e rua.

$$-60n=-360+60$$

Tāpirihia te -360 ki te 60, ka -300.

$$-60n=-300$$

Whakawehea ngā taha e rua ki te -60.

$$n=\frac{-300}{-60}$$

Whakawehea te -300 ki te -60, kia riro ko 5.

$$n=5$$