### Home > CC2 > Chapter 3 > Lesson 3.2.5 > Problem3-86

3-86.

Copy and complete each problem mentally.

1. $\frac { 5 } { 7 } \cdot \frac { 7 } { 5 } =\boxed {\phantom{a}}$

$1$

1. $\frac{8}{13}\cdot\boxed{\frac{\phantom{a}}{\ }}=1$

Look at part (a). What do you notice?

$\frac{13}{8}$

1. $\boxed{\frac{\phantom{a}}{\ }}\cdot\frac{31}{27}=1$

See part (b).

1. $\frac { 5 } { \boxed {\phantom{a}} } \cdot \frac { 2 } { \boxed {\phantom{a}} } = 1$

Look for patterns in parts (a) - (c).

1. What do all of the problems have in common?

Look at all of the answers and at all of the fractions.