Can someone show me how to work out this problem?

Heating 235 grams of water from 22.6 degrees Celsius to 94.4 degrees celsius in a microwave oven requires 7.06X10^4 joules of energy. if the microwave frequency is 2.88X10^10s^-1, how many quanta are required to supply the 2.06X10^4 joules?