Solve the system.

{j+k=3
{j−k=7

use the substitution method.

a. the solution is (5, −2).

b. there is no solution.

c. there are an infinite number of solutions.

d. the solution is (8, 1).

Simplify (1/2)4th power a. (1/16) b.(1/8) c.(1/4)

Set $r$ is a set of rectangles such that (1) only the grid points shown here are used as vertices, (2) all sides are vertical or horizontal and (3) no two rectangles in the set are congruent. if $r$ contains the maximum possible number of rectangles given these conditions, what fraction of the rectangles in set $r$ are squares? express your answer as a common fraction.

Given that sin∅ = 1/4, 0 < ∅ < π/2, what is the exact value of cos∅? a. (√4)/4 b. (√15)/4 c. (4π)/2 d. (4√2)/4