40 percents of student are boys in a karate class.There are 18 fewer boys than girls.How many students are in a karate class altogether?

3 answers

If there are s students,
b+g = s
b = 2/5 s
b = g-18
Now just find s
X girls,
x-18 boys,
40% are boys and 60% are girls,

X = 0.6(x + (x-18)),
X = 0.6*(2x-18),
X = 1.2x - 10.8,
X = 54 girls,

x-18 = 54 - 18 = 36 boys,

54 + 36 = 90 students.
simpler solution?

40% boys , 60% girls ... 20% or 1/5 difference

18 boys is 1/5 of class ... 90 students total