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

when the daily mileage is greater than 40 miles, unlimited mileage plan will save you money. 40 miles is the break-even point.

step-by-step explanation: