There are 2 ways to do this
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Method 1) Divide both sides by 25, then add 2 to both sides
25(M-2) = 650
M-2 = 650/25
M-2 = 26
M = 26+2
M = 28
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Method 2) Distribute the 25 through to each term inside the parenthesis. Then isolate for M by adding 50 to both sides, and then dividing both sides by 2.
25(M-2) = 650
25M - 50 = 650
25M = 650+50
25M = 700
M = 700/25
M = 28
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Either way the answer is 28