(d) Let the number of boys and girls participating in sports be 3x and 2x respectively. Then, 3x = 15 or x = 5. So, number of girls participating in sports = 2x = 10. Number of students not participating in sports = 60 – (15 + 10) = 35. Let number of boys not participating in sports be y. Then, number of girls not participating in sports = (35 – y). Therefore (35 – y) = y + 5 ⇒y = 15. So, number of girls not participating in sports = (35 – 15) = 20. Hence, total number of girls in the class = (10 + 20) = 30.