Hi there!
Like I said earlier that I can't solve #1 so I will only solve #2 and #3
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5^x = 7
First, we need to solve for the exponent x
log(5^x) = log(7)
x* (log(5)) = log(7)
x = log7/log(5)
x = 1.209062
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Please let me know when you post the #3