Use the fraction models to solve the addition equation. There are two sets of fraction models. The first set has three fraction models, with two completely shaded, and the last one is partitioned into twelve equal parts with four parts shaded. The second set has two fraction models, with one completely shaded, and the last one is partitioned into six equal parts, with three parts shaded. Below is the equation two and four twelfths plus one and three sixths equals blank line.

three and seven twelfths
three and ten twelfths
three and seven eighteenths
two and twelve seventy seconds