Level 3
A tank containing some water and 7 identical stones has a mass of 1 kg 235 g. When the 7 stones were taken out, the mass of the tank of water became 759 g. Find the mass of each stone.
(Give the answer in grams.)
Level 3 Jonas took one Math test. For every correct answer, he was awarded 4 points. For every wrong answer, 2 points were deducted. 21 out of 30 questions he answered were correct. How many points did he score?
Level 2
Mr Smith saved a total of $8540 in 6 months. In the first 4 months, he saved $1210 each month. In the 5th month, he saved $1530. How much did he save in the 6th month?