There are four boys to every five girls in an introductory geology course. If there are 387 students enrolled in the course, how many are boys?

172 boys.

Step-by-step explanation: The ratio of boys to girls is 4:5. We can say that the number of boys in the class is four multiplied by the common value that the ratio is based on. We can call this common value x and say that the number of boys in the class is 4x. Applying the same logic to the girls, we can say that there are 5x girls in the class. Thus, a total of 9x children. We divide the total value by 9 to get x, which equals 43. We can then retrieve the number of boys by calculating 4x, which equals 172.

a. turk and mcalister

b. howard, mission, and market

c. yes. since streets end some do not cross yet are not parallel to others. example: mcalister and 5th

step-by-step explanation:

parallel lines are lines which do not intersect ever and look a lot like railroad tracks. turk, mcalister and golden gate are examples of these.

intersect are streets which cross each other and a car on one can reach the other. howard, mission, and market intersect with 6th.

skew lines are lines which neither intersect nor are parallel. these lines exist here because some streets end and never intersect another like mcalister and 5th.