.. Solve using substitution.
2x - 5y = 12
x = -9

2x–5y = 12

2(–9)–5y = 12

–18–5y=12

–5y=12+18

–5y=30

y= –30/5

y= – 6

(x,y) —> (–9,–6)

i don't know

step-by-step explanation:

180°

step-by-step explanation:

sum of equilateral triangle=180°

< n=60°

< m=120°°[angle supplementary of equilateral angle]

< m+< r+< x=360°(sum of exterior angle of triangle)