Start by rounding each of the numbers you're working with. Round 1.2 down to 1.Round .7 up to 1.Round 1.9 up to 2. So Luis rode his bike about 1 mile to his friend's house, then about 1 mile to the video store, then about 2 miles to the library. Add the numbers together to find out how far he traveled from his house to his friend's house to the video store to the library. 1 + 1 + 2 = 4, so he rode about 4 miles. If he rode the same route back home, then multiply that by 2, since he traveled the same distance twice. 4 x 2 = 8. So Luis traveled about 8 miles in all.