The other tutor only gave you an approximate decimal solution using
a calculator. That's not what your teacher wants. Your teacher wants
an exact answer. Here's the way to do it using fraction exponents:
Write both 12's as 22·3
Write the square root as the power
and the cube root as the power:
Make everything have an exponent by giving a 1 exponent
to whatever doesn't have an exponent showing:
Remove the inner parentheses by multiplying exponents:
Add the exponents of 2 and the exponents of 3
Change mixed number exponent to
Remove the remaining parentheses by multiplying exponents:
Erase the 1 exponent and change the exponent to a square root
Edwin