There are 60 students in a class. The number of girls is three times the number of boys. How many girls are in

the class?

Answer: 45 girls

B = number of boys

G = number of girls

G = 3*B since there are 3 times as many girls compared to boys

B+G = 60

B+3B = 60 ... replace G with 3B, solve for B

4B = 60

4B/4 = 60/4

B = 15, so there are 15 boys

G = 3*B

G = 3*15 ... plug in value of B

G = 45, and 45 girls

as a check

B+G = 15+45 = 60, so that works out

45 girls in the class