Answer:
m=43.39 Kg
Explanation:
from conservation principle we have
heat gained by  ice equal to heat lost by coffee
heat gained by ice = heat from -15 °C ice to 0 °C ice + 0 °C ice to 0 °C water + 0 °C water to 65 °C water
                 = m*S1*15 + mL + ms2 *65
where s is specific heat of respective phase
                = m(2.08 *15 + 334.16 + 4.184 *65)
                = m*637.32
heat lost by the coffee= ms* delta T
                   =0.3 *4190 *(87-65)
                   =27654
therefore
27654 Â = m*637.32
m=43.39 Kg
