Answer:

Step-by-step explanation:
<u>Factor by grouping</u>
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4 x 2 = 8 its impossible to have 7 and 8 units
35 can't be divided by 4
the answer left is 28 units, which can be multiplied by 4
7 x 4 = 28
The answer is 28 units
Number of red marbles in bag = r. b = 10-rProbability of first marble being red: r/10Second marble being red: (r-1)/9total probability = 2/15 = (r-1)*r/90r = 4b = 6