Phillip has x marbles. His father gave him 2 times the number of marbles he has. Now he has 21. How many marbles did Phillip have before?

Afactory adds 3 red drops and 2 blue drops of coloring to white paint to make each pint of purple paint. the factory will make 50 gallons of the purple paint. how many drops of red and blue coloring will the factory need in the 50 gallon batch of purple paint.

Ben is three times as old as samantha, who is two years older than half of michel's age. if michel is 12. how old is ben?

Can someone check if i did this right since i really want to make sure it’s correct. if you do you so much