I don't even understand how this question works. How do I solve it?

Question

A microwave oven heats by radiating food with microwave radiation, which is absorbed by the food and converted to heat. suppose an oven's microwave is 13.7 cm. a container w/ 175 mL of water was placed in the oven and the temp rose from 23.2 dgerees c to 98.7 degrees c. how many photons of this microwave radiation were required? assume all the energy from the radiation was used to raise the temp of the h20.

i would show some work but i don't even know where to begin. :[

Answer 1

q absorbed by water = mass x heat capacity x delta T. Calculate amount of heat generated by oven. q will be in joules.
Then Energy = hc/lambda.
h is Planck's constant, c is speed of light in meters/sec and you have lambda (I guess 13 cm is lambda but you don't say that). That will give you energy of the microwave for 1 photon. You should be able to take it from there.

Answer 2

thanks a bunch!