According to the rule x △ y = 3x-2y, then x △ (4 △ 1) = 7, find x =? (the four operation rules remain unchanged)

According to the rule x △ y = 3x-2y, then x △ (4 △ 1) = 7, find x =? (the four operation rules remain unchanged)

4△1
=3×4-2×1
=10
So x △ (4 △ 1) = x △ 10 = 7
3x-2×10=7
x=9