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Yolo4mecuite
Explain how you can show that -3 is a solution of x + 7 = 4.
Isolate the variable. x+7=4 -7 -7 x = -3
That's it really. Just do everything to both sides.
one way is replace x with -3 in x+7=4 replace the x with -3: -3 + 7 = 4 now do the arithmetic: -3+7 is 4, so you get 4=4 this is true, so x=-3 is a solution.