directly proportional
photos _______ minutes
28 -------------------- 8
21 -------------------- t
\(\frac{28}{21} = \frac{8}{t}\)
Multiply cross
\(28*t = 21*8\)
\(28t = 168\)
\(t = \frac{168}{28}\)
\(\boxed{t=6}\)
To print twenty-one photos will take six minutes
