standard_description: Generate measurement data by measuring lengths using rulers marked with halves and fourths of an inch. Show the data by making a line plot, where the horizontal scale is marked off in appropriate units— whole numbers, halves, or quarters.
problem_activity: Solve.
a.
$${{7\over8}-{4\over8}}$$
b.
$${{5\over10}+{3\over10}}$$
c.
$${1-{2\over5}}$$


aligns: no