Answer:
Moira =13 years, Morag =10 years, Muriel =18 years
Step-by-step explanation:
Moira =x
Morag =y
Muriel =z
x=y+3=>y=x-3
x=z-5=>z=x+5
=>
x+x-3 +x +5 =41
3x=41 - 5 +3
3x=39
x=39 :3
x=13 (Moira is 13 years)
y=13-3 =10 (Morag is 10 years)
z=13 +5 =18 (Muriel is 18 years)