1 - Determine quantos múltiplos de 9 há entre 100 e 1 000. 2 - Determine o 20º elemento e a soma dos termos da seguinte progressão aritmética: (2, 7, 12, 17,...).​

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1. isolate the variable, in this case, d. subtract 35.5 on both sides of the equation.2. 52 subtracted by 35.5 is 16.53. therefore your answer would be d= 16.5this is the basics of pre algebra, isolating variable through adding, subtracting, multiplying, and dividing, if you have any other questions to ask just comment!