Answer:
x*2=y+x= both
Step-by-step explanation:
y would be her sister age, you would have to multiply Marias age by 2 to get her sisters age since her sister is twice her age then you have to add them together to get the sum of both their ages.
Example: maria is 16
16*2=32+16=48
so the sum of both of their ages is 48 (JUST AN EXAMPLE)