Haro has 17 model cars, 31 model trucks, and 9 model airplanes on the shelf in his room. his sister thought it would be funny to hide all the red models. now haro only has 39 models on his shelf. which number sentence could be used to find how many red models his sister hid?
a. (17 + 31 + 9) – r = 39
b. 17 + 31 + 9 + r = 39
c. (17 + 31 + 9) + r = 39
d. 39 + 17 + 31 + 9 = r

If 1 km = 0.621 miles, how many miles are in a centimeter

Lassify the function as linear or quadratic and identify the quadratic, linear, and constant terms. f(x) = (3x + 2)(−6x − 3) linear function; linear term: −21x; constant term: −6 linear function; linear term: −18x2; constant term: −6 quadratic function; quadratic term: 6x2; linear term: 24x; constant term: −6 quadratic function; quadratic term: −18x2; linear term: −21x; constant term: −6

Jeffery conducted a survey in his school and found that 30 of the 50 eighth grade students' favorite subject is mathematics. based on the results, jeffery concluded that out of the 200 students in his school, 120 students' favorite subject is mathematics. select the statement that is true about jeffery's conclusion. a. jeffery's conclusion is not valid because the sample was biased since only 200 students were surveyed. b. jeffery's conclusion is valid because the sample was random since all of the students were eighth grade students. c. jeffery's conclusion is valid because the sample was random. d. jeffery's conclusion is not valid because the sample was biased since all of the students were eighth grade students.