Every student enrolled in a science course is either a physics major or a biology major. if the ratio of physics majors to biology majors is 3 to 1 and there are 21 physics majors enrolled, how many biology majors are enrolled in the course?

Compare the subtraction problems 6/8 - 5/8 = 1/8 and 6/9 - 7/9 = 1/9 why is the answer to the first problem positive and the answer to the second problem negative

Awoman has 14 different shirts: 10 white shirts and 4 red shirts. if she randomly chooses 2 shirts to take with her on vacation, then what is the probability that she will choose two white shirts? show your answer in fraction and percent, round to the nearest whole percent.

Write the standard form of an equation with (see picture below)