7 Anny
The ratio of boys to girls in sixth grade is 3:4. If there are 48 girls, what is the total number of sixth graders?

Work Shown

B = number of boys

G = number of girls

Since the ratio of boys to girls is 3:4, this means

B = 3x

G = 4x

where x is any positive integer. The ratio 3x:4x reduces to 3:4 when we divide both parts by x.

Since there are 48 girls, we know that G = 48. We also know G = 4x. Equate the two items and solve.

4x = 48

x = 48/4

x = 12

This means

B = 3x

B = 3*12

B = 36

So we have 36 boys and a total of B+G = 36+48 = 84 students.

Here's another way to figure out how many boys there are in the class.

(number of boys)/(number of girls) = 3/4

B/G = 3/4

B/48 = 3/4 plug in G = 48

B*4 = 48*3 ... cross multiply

4B = 144

B = 144/4 divide both sides by 4

B = 36