The fourth power of 3 multiplied by the fifth power of 3 minus the second power of 3 multiplied by the sixth power of 3 plus the seventh power of 3 multiplied by negative 3

The fourth power of 3 multiplied by the fifth power of 3 minus the second power of 3 multiplied by the sixth power of 3 plus the seventh power of 3 multiplied by negative 3

3^4*3^5-3^2*3^6+3*(-3)^7
=3^9-3^8-3^8
=3^8