William H. | SAT, ACT and other TutoringSAT, ACT and other Tutoring

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The way you solve problems like this is use algebra to get the variable(in this problem n) on the left and the numbers on the right.

The first step is to solve 3(n-7) which can use the distributive property to show that this equals 3(n) - (3)(7) which equals 3n - 21. This means the equation is now -17 + 4n = 3n - 21

The next step is to add 17 to each side. This means that the equation is now 4n = 3n - 4

Next we subtract 3n from each side leaving us with n = -4.

Therefore, the answer is n = -4.

Let me know if this is still unclear. I would be happy to explain it more.