At a country concert the ratio of the number of boys to the number of girls is 2: 7 if there are 250 more girls than boys how many boys are at a concert

At the country concert, the ratio of boy to girls = 2 : 7
Now, there are 250 more girls than boys, how many boys are there in the concert.
the equation would be like this:
Let x = girls
Let y = boys
=> y /x = 2/7
=> y + 250 = x
=> y + 250 = 7/2y
=>  y = 100
The number of boys is 100
=> x = 100 + 250
=> x = 350, the number of girls.