`\text{Ta có :} \hat{aAb} = x = 70^0 \text{(đối đỉnh)}`
`\text{Lại có :} \hat{aAB} + y = 180^0 (kề bù)`
`=> 70^0 + y = 180^0`
`=> y = 180^0 - 70^0`
`=> y = 110^0`
`\text{Có :} t = \hat{ABb} = 80^0`
`\text{Có :} t + z = 180^0`
`=> 80^0 + z = 180^0`
`=> z = 100^0`
Vậy `x = 70^0 ; y = 110^0 ; z = 100^0 ; t = 80^0`