Gino can paint 6 fence panels in 4 hours, while Danish can paint 7 fence panels in 5 hours. Gino and Danish work together to paint a total of 21 panels. If they continue to paint at the same rate, how long will it take them to paint 21 panels? Give your answer in hours and minutes, correct to the nearest minute. Answer ... h ... min

1. Find Gino's and Danish's individual painting rates.

Gino's rate $= \dfrac{6}{4}=\dfrac{3}{2}$ panels per hour.

Danish's rate $= \dfrac{7}{5}$ panels per hour.

2. Find their combined rate and the time taken for 21 panels.

Combined rate
$=\dfrac{3}{2}+\dfrac{7}{5}$
$=\dfrac{15}{10}+\dfrac{14}{10}=\dfrac{29}{10}$
panels per hour.

Time taken
$=21\div \dfrac{29}{10}$
$=21\times \dfrac{10}{29}=\dfrac{210}{29}$
hours.

3. Convert the time to hours and minutes, correct to the nearest minute.

$\dfrac{210}{29}=7.241379\ldots \text{ hours}$

Fractional part:
$0.241379\ldots \times 60=14.4827\ldots \text{ minutes}$

Correct to the nearest minute, this is $14$ minutes.

So the time taken is $7$ h $14$ min to the nearest minute.