1. is -7 + 9= -9 + 7 true, false, or open a. true b. false c. open 2. is 4x - 3 = 19 true, false, or open a. true b. false c. open 3. which of the following is a solution to the equation 16 = 4x - 4 a. -5 b. -4 c. 5 d. 16 4. an art student wants to make a model of the classroom. the length of the classroom is 2.4 times its width. the length of the student's model is 42 in. what should the width of the model be? a. 17.5 in b. 20.5 in c. 83.6 in d. 100.8 in 5. use mental math to determine the solution to x - 3 = 10 a. x=7 b. x=13 c. x=30 d. x=0