To ensure the longevity and beauty of your arrangement of 10 red roses and 10 pink roses in a glass vase, here are some flower care tips:

1. **Trimming Stems**: Upon receiving the roses, trim the stems at a diagonal angle with sharp scissors. This encourages better water absorption.

2. **Selecting a Vase**: Choose a clean glass vase that is tall enough to support the length of the rose stems. Fill the vase with lukewarm water.

3. **Removing Foliage**: Remove any leaves from the lower part of the stems that may sit in the water. This prevents bacterial growth and keeps the water clean.

4. **Water Level**: Ensure that the water level in the vase is sufficient to cover at least 2-3 inches of the stem ends. Check the water level daily and top up as needed.

5. **Water Quality**: Use clean, room temperature water. Replace the water every 2-3 days to prevent bacterial buildup and keep the flowers fresh.

6. **Location**: Place the vase in a cool area away from direct sunlight and heat sources. This helps prolong the life of the roses.

7. **Avoiding Ethylene**: Keep the roses away from fruits or vegetables, as they release ethylene gas which can cause flowers to wilt faster.

8. **Pruning**: Remove any wilting or spent blooms from the arrangement promptly to maintain its appearance.

With these care tips, your arrangement of red and pink roses will stay fresh and beautiful for longer, adding a touch of elegance to your space.