There are 7 students in a class: 5 boys and 2 girls.
if the teacher picks a group of 4 at random, what is the probability that everyone in the group is a boy?

The sum of the product of 4 and x and the product of 7 and y is 61. the sum of the product of 12 and x and the product of 21 and y is 61. what are the values of x and y?

How do you use the elimination method for this question? explain, because i really want to understand!

Asmall business produces and sells balls. the fixed costs are $20 and each ball costs $4.32 to produce. each ball sells for $8.32. write the equations for the total cost, c, and the revenue, r, then use the graphing method to determine how many balls must be sold to break even.