A total of 520 students sat for the Mathematics mock test. ⁴₅ of the boys and ⁷₈ of the girls passed the mock test. The same number of girls and boys failed the mock test. How many more girls than boys passed the mock test?
Fraction of the boys that failed the mock test
= 1 - ⁴₅
= ¹₅

Fraction of the girls that failed the mock test
= 1 - ⁷₈
= ¹₈

Number of boys and girls that failed the mock test is the same. Make the numerators the same.
¹₅ Boys = ¹₈ Girls

Total number of boys = 5 u
Total number of girls = 8 u

Total number of students
= 5 u + 8 u
= 13 u

13 u = 520

1 u = 520 ÷ 13 = 40

Number of boys that passed the mock test = 4 u
Number of girls that passed the mock test = 7 u

Number of more girls than boys who passed the mock test
= 7 u - 4 u
= 3 u
= 3 x 40
= 120

Answer(s): 120