Answer: 18 miles.
Step-by-step explanation:
We can think on this as a triangle rectangle, where one cathetus is 12miles, and the other cathetus is 5 miles. (so the vertex of the triangle rectangle are Annie's house, the school, and the store)
The path that Annie would do is:
From her house to the store (so she drives 5 miles)
And from the store to the school, so here she drives through the hypotenuse of the triangle rectangle.
Then we need to find the length of this triangle rectangle.
We know that the square of the hypotenuse is equal to the sum of the squares of the cathetus, then:
H^2 = (12mi)^2 + (5mi)^2
H = √( (12mi)^2 + (5mi)^2) = 13mi
Then she first drives 5 miles from her house to the store, and then drives 13 miles from the store to the school, then the total distance that she drives is:
5 miles + 13 miles = 18 miles.