claire's age = x
claire's mothers age = 2x+4 ( 4 more than twice claire's age)
sum is addition
x + 2x+4 = 58
add like terms ( x +2x = 3x)
3x +4 = 58
subtract 4 from each side:
3x = 54
divide both sides by 3
x = 54 /3
x = 18
Claire is 18 years old
Claire's mother is 2*18 = 36 +4 = 40 years old