I heard this question in an online discussion, asking about the value of art and it bothered me enough to make this post!
All forms of art develop soft skills required for successful careers such as problem solving, perseverance and concentration to name a few. Here are more: Top 10 skills Children learn from the arts
9 Reasons to study art (in Highschool) - many of these apply to elementary students too
Why study art? Tate video including the voices of artists, youth and major cultural figures
Music IS Literacy (from MusicPlayOnline.com)
There are so many connections between math and art, particularly in geometry. Some art/math activities I did in the past are tessellations and symmetry drawings. There are many other activities you can do:
Here are more links to the connection between Math and Art:
Visual examples of math in art ttps://www.learning-mind.com/examples-of-art-and-math/
Need a Study.com subscription - How Math Models are used in art