can someone tell me what to do on this question?

(4�ã7+�ã2)(�ã3-3�ã5)

I have a sneaky suspicion that you mean :

(4√7+√2)(√3-3�√5)

Just follow the usual FOIL method of multiplying two binomials

= 4√21 - 12√35 + √6 - 3√10