Set up a system of equation:
p+m=53
m=2p+11
Use the substitution method to for "m"
p+(2p+11)=53
3p+11=53
3p=42
p=14
Put "p" into either equation to solve for "m"
m=2(14)+11
m=28+11
m=39
Check by plugging both "p" and "m" into both equations to make sure they work:
14+39=53
53=53
That one works, now let's check the other one
39=2(14)+11
39=28+11
39=39
They both work!
Petra is 14 years old, and her mother is 39 years old
