Number of boys = 720Probability of boy studying French is 2/3, so 2/3 of 720 boys study French.720 students * 2/3 = 240 * 2 students = 480 students

Number of girls = 7003/5 girls study French.700 students * 3/5 = 140 * 3 students = 420 students

Total number of students studying French480 students + 420 students = 900 students