If a car is traveling at 10 miles per hour on a slippery road, then its stopping distance d in feet can be calculated by d=100/10 × 1/x

Galen sold tickets of his church’s carnival for a total of $2,820. children’s tickets cost $3 each and adult tickets cost $5 each. the number of children’s tickets sold was 30 more than 3 times the number of adult tickets slod. how many children’s ticket and how many adult tickets did he sell?