Answer:
b = 5 grams
Explanation:
Let b represent the weight of one ball.
Then 9b = 20 grams + 5b.
Solving for b, subtract 5b from both sides, obtaining 4b = 20 grams.
Then b = the weight of one steel ball = 5 grams.
Check: Does 9(5 grams) = 20 grams + 5(5 grams)?
Does 45 grams = 45 grams? YES