Ravi had some marbles in a jar. He added 20 marbles and removed 8 marbles. Then a magic trick doubled the number of marbles in the jar. There were then 70 marbles. How many marbles were in the jar before he added or removed any?
Opening the drawing…
MathBrush is being tested with a few parent groups, and every solution on the site is open to them. If you were given a code, it goes in once and this device remembers it. 65 worked examples are free to everyone without one.