Show your work, give an explanation, and provide java code for your solution.

Draw an arithmetic expression tree that has four external nodes, storing the numbers 1, 5, 6, and 7 (with each number stored in a distinct external node, but not necessarily in this order), and has three internal nodes, each storing an operator from the set { + * / h, so that the value of the root is 21. Any of these operators may be used more than once, and they are real (not integer) operators, i.e., they may operate on and return fractions