There were 20% more boys than girls in a swimming club. After 50 girls left, there were twice as many boys as girls in the club. How many boys were there in the club?
b = 1.2g
b = 2(g-50)
so,
1.2g = 2g-100
.8g = 100
g = 125
so, b = 150
b = 2(g-50)
so,
1.2g = 2g-100
.8g = 100
g = 125
so, b = 150