Decompose the fraction into the sum of its unit fractions. (3 points)
seven tenths
a
one tenth plus one tenth plus one tenth
b one tenth plus one tenth plus one tenth plus one tenth plus one tenth
c one tenth plus one tenth plus one tenth plus one tenth plus one tenth plus one tenth plus one tenth
d one tenth plus one tenth plus one tenth plus one tenth plus one tenth plus one tenth plus one tenth plus one tenth plus one tenth