In the morning, Mrs Chen baked muffins of 3 different flavours - chocolate, strawberry and vanilla. The ratio of the number of chocolate muffins to the number of strawberry muffins was 3 : 5. There were 28 more strawberry muffins than chocolate muffins. There were 10 more vanilla muffins than strawberry muffins.

1. Find the value of 1 unit using the difference between strawberry and chocolate muffins

Difference in units $= 5 - 3 = 2$ units
$2 \text{ units} = 28$
$1 \text{ unit} = 28 \div 2 = 14$

2. Calculate the number of strawberry muffins and then vanilla muffins

Number of strawberry muffins $= 5 \times 14 = 70$
Number of vanilla muffins $= 70 + 10 = 80$

1. Find the initial number of chocolate, strawberry, and vanilla muffins from the given ratios and differences.

Difference in ratio between strawberry and chocolate $= 5 - 3 = 2$ units.
$2 \text{ units} = 28$
$1 \text{ unit} = 14$
Initial chocolate muffins $= 3 \times 14 = 42$
Initial strawberry muffins $= 5 \times 14 = 70$
Initial vanilla muffins $= 70 + 10 = 80$

2. Calculate the new total number of chocolate and vanilla muffins.

The number of strawberry muffins remains unchanged at $70$.
New total of chocolate and vanilla muffins $= 3 \times 70 = 210$

3. Determine the number of chocolate muffins baked in the afternoon using the percentage increase.

$8\% \text{ of } 42 = 0.08 \times 42 = 3.36$
$10\% \text{ of } 42 = 0.10 \times 42 = 4.2$
The number of muffins must be a whole number. The only integer between $3.36$ and $4.2$ is $4$.
Therefore, $4$ chocolate muffins were baked in the afternoon.

4. Calculate the number of vanilla muffins baked in the afternoon.

New number of chocolate muffins $= 42 + 4 = 46$
New number of vanilla muffins $= 210 - 46 = 164$
Vanilla muffins baked in the afternoon $= 164 - 80 = 84$