For the first one,
you multiply 5x and -5 to get -25.
Then you move the constant to the right and change the sign to get 3x= -21 +25.
Calculate the sum of -21+25 to get 4.
Divide both sides of the equation by 3 to get x=4/3.
So then your final answer is x=4
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3
For the second one,
Distribute 7 through the parentheses to get 14x + 14+8=120
The you add 14+8 to get 22. Your equation should be 14x+22=120
Move the constant to the right side and change its sign to get 14x=120-22
Subtract 120-22 to get 98. Now your equation should be 14x=98
Divide both sides of the equation by 14 to get x=7.
Your finial answer for the second one should be x=7.
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I hope this made sense.