[tex] \frac{1}{4} + \frac{1}{5} = \frac{1}{t} \\ \frac{1 \times 5}{4 \times 5} + \frac{1 \times 4}{5 \times 4} = \frac{1}{t} \\ \frac{5}{20} + \frac{4}{20} = \frac{1}{t} \\ \frac{9}{20} = \frac{1}{t} [/tex]
I WILL USE CROSS MULTIPLICATION
[tex]t(9) = 20 \\ 9t = 20 \\ \frac{9t}{9} = \frac{20}{9} \\ t = \frac{20}{9} [/tex]
GOODLUCK.
