Hello i just need help with this question please and thank you

stay safe from corona:)

hope you're doing well today!,

Step-by-step explanation:

<2 + <3 = <1. it doesn't say if <1 is also 90º but you know it will be because the measure of a line if 180º so just add and subtract, you'll see that <1 is 90º.

also <5 = <3 because of vertical angles.

<6+<7 = 180º (straight line definition)

<9 = <11, < 8 = <10 both vertical angles

hope this helps, ask if you need additional help!!

answer: the answer is one

step-by-step explanation:

pemdas, in this situation there is no parenthesis or exponents so you go to multiplication, 1x1=1, then division 1/1= 1 then addition 1+1=2 then subtraction 2-1=1