Answer:
24 years old
Step-by-step explanation:
Let the age of Blake be x and the age of Heather by y then...
x=7+y
7+x+7+y=55
Notice we are adding additional 7s because the question states "in 7 years"
Simplify the second equation...
7+x+7+y=55
14+x+y=55
Subtract 21 from both sides
x+y=41
Solve using substitution (substitute 7+y for x since x = 7+y)
7+y+y=41
Combine like terms
2y+7=41
Subtract 7 from both sides
2y=34
Divide both sides by 2
y=17
x=7+17=24
Blake is 24 years old now
