Answer:
y=20º
Step-by-step explanation:
RPS+SPM+MPN is 180º
so:
4y-10+90+y=180
simplify
5y+80=180
subtract 80 from both sides
5y=100
divide by 5 on both sides
y=20
line RPN = 180 = 4y - 10 + 90 + y
180 - 90 + 10 = 5y
100 = 5y
y = 100/5
y = 20
