At a banquet the ratio of the number of boys to the number of girls is 5:3. Halfway through the banquet 20 boys leave and the ratio becomes 5:4. How many girls are at the banquet?
x=number of boys
y=number of girls.
we suggest this system of equations:
We solve this problem by substituion method.
(5y/3 - 20)/y=5/4
4(5y/3 - 20)=5y
least common multiple= 3
Answer: there are 48 girls at the banquet.