15. In a school, the ratio of boys and girls is 4:5, when 100 girls leave the school, the ratio becomes 6:7. How many boys are there in the school​

Step-by-step explanation:

the ratio of boys and girls is equal to 4:5

let the number of boys be x

and the number of girls be y

so form 1st statement

x:y=4:5

now 2nd statements

x:y-100=6:7

Therefore solving equations 1 and 2

x=1200

y=1500

hello from mrbilldoesmath!

answer:

the domain is the set { -2, 0, 2, 3}

discussion:

the domain is the set of x values in the ordered pairs (x,y). taking the x, or first component, of each ordered pair gives   -2, 0, 2, 3.

you,

mrb