Explanation:
a.
if her cousin is 10 years old Clare would be 15 years old
because 10+5 = 15
if her cousin is 2 years old Clare would be 7 years old
because 2 + 5 = 7
if her cousin is x years old Clare would be x+5 years old
because x+ 5 = x+ 5
b. Clare's cousin is 7 years old
because 12 - 5 = 7